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FARM MOTORS 



STEAM AND GAS ENGINES, HYDRAULIC 

AND ELECTRIC MOTORS, TRACTION 

ENGINES, AUTOMOBILES, ANIMAL 

MOTORS, WINDMILLS 



BY 
ANDREY A. JOTTER 

MEMBER AMERICAN SOCIETY OF MECHANICAL ENGINEERS, DEAN OF THE ENGINEERING 

DIVISION AND PROFESSOR OF STEAM AND GAS ENGINEERING 

IN THE KANSAS STATE AGRICULTURAL COLLEGE 



Second Edition 
Revised and Enlarged 



McGRAW-HILL BOOK COMPANY, Inc. 

239 WEST 39TH STREET. NEW YORK 



LONDON: HILL PUBLISHING CO., Ltd. 

6 & 8 BOUVERIE ST., E.C. 
1917 






Copyright, 1913, 1917, by the 
McGraw-Hill Book Company, Inc. 




M -2 191? 

THE /MAPLE PRESS YORK PA 

©CI.A462826 






PREFACE TO SECOND EDITION 

The first edition of this book was published in 1913. It was 
new in its field and the experience since gained in teaching farm 
motors has led to the present revision. 

In this edition the chapters on gas and oil engines and on 
traction engines were enlarged, the steam engine chapters were 
rewritten and new chapters were added on automobiles and on 
animal motors. All other chapters were revised. 

In the preparation of this edition, the author is particularly 
indebted to President J. H. Waters and to his colleagues N. A. 
Crawford, W. A. Buck, E. V. Collins and F. A. Wirt of the Kan- 
sas State Agricultural College. A. A. Potter. 

Manhattan, Kansas, 
April 10, 1917. 



'i..t' 



PREFACE 

In preparing this book it has been the intention to include the 
fundamental principles governing the construction, working and 
management of motors which are suitable for farm use. The 
motors treated include steam engines, gas and oil engines, trac- 
tion engines, automobiles, water motors, windmills and electric 
motors. 

The method followed in each chapter was to give: 

1. the fundamental principles underlying the particular motor, 

2. the principal parts of the motor, 

3. auxiliary parts, 

4. uses to which the particular type of motor is adapted. 

5. selection, erection and management of the different machines. 
While this book was prepared primarily as a text-book for 

students in agricultural engineering, the subject matter is so pre- 
sented that it will be of equal value to farmers and to operators 
of various kinds of engines and motors. Much practical informa- 
tion is included regarding steam, gas and electricity, and the text 
is illustrated with over 275 cuts. 

Some space is devoted to the more refined methods used in 
engineering practice for improving the economy of various 
motors. While many of these methods are not used at the pres- 
ent time in connection with farm motors, it is the opinion of the 
author that a knowledge of the best engineering practice is not 
only of considerable educational value, but will lead to the more 
perfect manipulation of the simple farm motors. 

The successful rural engineer of the near future will be the 
man that applies proven engineering to the machinery and con- 
structions used on the farm. 

The author is particularly indebted in the preparation of this 
book to Professors E. B. McCormick, M. R. Bowerman, R". A. 
Seaton, and W. W. Carlson, of the Kansas State Agricultural 
College; to Professors Allen and Bursley of the University of 
Michigan; and to Mr. S. Yesner of Boston, Mass. 

A. A. Potter. 
Manhattan, Kansas, 
November, 1913. 



CONTENTS 

Page 

Preface v 

CHAPTER I 

Farm Motors in General 1 

Sources of energy — Principles governing the action of various 
mechanical motors — Animal motors — Comparison of various types 
of motors — Power used on farms — Comparative cost of power with 
various motors — Problems. 

CHAPTER II 

Fundamental Principles and Definitions 6 

Matter — States of matter — Motion — Force and pressure — Work, 
energy and power — Horsepower — Indicated horsepower — Brake 
horsepower — Draw-bar horsepower — Nature of heat — Tempera- 
ture — Thermometers — Units of heat — Mechanical equivalent of 
heat — Specific heak — Specific gravity — Problems. 

CHAPTER III 

Steam Generation and Steam Boilers 16 

Theory of steam generation — Fuels — Combustion — Commercial 
value of fuels — Principal parts of a steam power plant — Classifica- 
tion of boilers — Return tubular boiler — Vertical fire-tube boilers — 
Water-tube boilers — Grates for boiler furnaces — Piping for boilers 
— Pipe fittings — Valves — Safety valves — Steam gages — Water glass 
and gage cocks — Water column — Steam traps — Feed pumps and 
injectors — Feed-water heaters — Chimneys and draft-producing 
systems — Firing — Rating of boilers — Management of boilers — 
Problems. 

CHAPTER IV . 

Stationary Steam Engines 42 

Description of the steam engine — Action of the plain slide valve — 
Types of steam engine valve gears — Valve setting — Steam engine 
indicator cards — Losses in steam engines — Steam engine governors 
— Engine details — Lubricators — Steam separators — The steam lo- ' 
comotive or Buckeymobile — Steam turbines — Installation and care 
of steam engines — Problems. 



x CONTENTS 

Page 

CHAPTER V 

Gas and Oil Engines 65 

The internal-combustion engine — The gas engine cycle — Classifica- 
tion of gas engines — The four-stroke cycle — The two-stroke cycle 
engine — Comparison of two-stroke cycle and four-stroke cycle 
engines — Gas engine fuels — Gasoline and other distillates of crude 
petroleum — Alcohol as a fuel for gas engine use — Essential parts of 
a four-stroke cycle gas engine — Carburetors for gasoline engines — 
Carbureting kerosene and the heavier fuels — Cooling of gas engine 
cylinder walls — Gas engine ignition systems — Electric ignition 
systems for gas engines — The make-and-break system of ignition— 
The jump spark system of ignition — Ignition dynamos — Magnetos 
— Low-tension magnetos — High-tension magnetos — Timers — Auto- 
matic ignition for oil engines — Lubrication of gas and oil engines — 
Governing of gas engines — The gasoline engine on the farm — 
Selecting a gas engine — Installation of gas engines — Instructions 
for operating gas engines — Care of a gas engine — Problems. 

CHAPTER VI 
Automobiles 122 

Types of automobiles — Essential parts of a gasoline automobile 
Automobile motors — Clutches — Transmission gears — The progres- 
sive sliding-gear transmission system — The selective sliding-gear 
transmission system — The planetary transmission system — The 
friction drive — Differentials for automobiles — Universal joint — 
Front and rear axles — Steering and control systems — Brakes — 
Wheels and tires — Carburetors and gasoline feed systems — Ignition 
—Automobile lubrication — Automobile starting systems — Auto- 
mobile lighting and accessories — Management of automobiles — 
Gasoline motor cycles — Problems. 

CHAPTER VII 

Traction Engines 168 

Fundamental parts of a traction engine — Steam traction engines — 
Boilers — Pumps — Feed-water heaters — Engine types — Reversing 
mechanisms for steam traction engines — Steering — Transmission 
systems and differentials — Gas traction engines — The gas traction 
engine motor — Carburetors for traction engines — Ignition for gas 
traction engines — Transmission systems and differentials — Type 
of traction — Uses of traction engines — Development of the gas trac- 
tion engine — Economy of gas traction engines — Rating of traction 
engines — Operation and care of traction engines — Problems. 

CHAPTER VIII 

Water Motors 211 

Determining the power of streams — Types of water motors — Over- 



CONTENTS xi 

Page 

shot, undershot and breast wheels — Impulse water motors — Water 
turbines — The hydraulic ram — Problems. 

CHAPTER IX 

Windmills 221 

Types of windmills — Principal parts of a windmill — The wind-wheel 
— The rudder or vane — The governor — Windmill gearing — Wind- 
mill brake — Towers — Method of erecting windmills — Care of wind- 
mills — Power of windmills — Uses of windmills — Problems. 

CHAPTER X 

Electric Motors, Generators and Batteries 236 

Action of electricity — Units of electricity — Ohm's law — Incandes- 
cent lamps — Wires for conductors of electricity — Electrical batter- 
ies — Primary batteries — Storage batteries — The lead storage bat- 
tery — The Edison storage battery — Methods of connecting bat- 
teries — The electric generator — Action of the electric generator — 
Direct and alternating currents — Principal parts of generators and 
motors — Classification of generators and motors — Series-wound 
generators — Series-wound motors — Shunt-wound generators — 
Shunt-wound motors — Compound-wound generators — Compound- 
wound motors — Various types of motors compared — Distribution 
of electric current — Electric meters — Fuses and circuit breakers — 
Switches and rheostats — Method of connecting motors — The elec- 
tric motor on the farm — The farm electric light plant — Installation 
of electric motors and generators — Starting and stopping motors — 
Starting and stopping generators — Care of motors and generators 
— Problems. 

CHAPTER XI 

Animal Motors 272 

The horse — Selection of a draft horse — Capacity and power of 
draft animals — Selection of feed for the horse — The mule — The ox 
— Cost of animal power — Problems. 

CHAPTER XII 

Mechanical Transmission of Power 278 

Belts — Leather belts — Rubber belts — Canvas belts — Care of belts 
— Method of lacing belts — Pulleys — Method of calculating sizes of 
pulleys — Quarter-turn belt — Chain drives — Rope transmission — 
Friction gearing — Toothed gearing — Shafting — Problems. 

Index 293 



FARM MOTORS 

CHAPTER I 
FARM MOTORS IN GENERAL 

A motor is an apparatus capable of doing work. Not consid- 
ering animal motors, which include men, horses and other animals, 
the mechanical motors available for farm use are: heat engines, 
including steam, gas, oil, hot-air and solar engines; pressure 
engines such as waterwheels and water motors; windmills; 
electric motors. 

Sources of Energy. — The principal source of all energy is 
the sun. It causes the growth of plants which furnish food 
for man and animals. The great coal deposits are only the 
result of the storing up of the sun's rays in plants in bygone 
days. These rays are also responsible for the raising of water 
from sea level to mountain top, thus giving it energy which can 
be utilized to turn waterwheels and made to do useful work. 

On the other hand, while the sun's rays are the fundamental 
sources of all energy, they can be utilized directly by man only 
to a very limited extent. The secondary sources of energy are 
the wind, waterfalls, carbon in different forms, such as coal, 
petroleum, or gas, and chemicals used in electric batteries. 

Principles Governing the Action of Various Mechanical 
Motors. — All mechanical motors do work by virtue of motion 
given to a piston, to blades on a wheel, or to an armature by some 
substance such as water, steam, gas, air, or electricity. The first 
requirement is that the above-mentioned substance, often called 
the working substance, be under considerable pressure. 

This pressure in the case of the water motor or waterwheel 
is obtained by collecting water in dams and tanks, or by utilizing 
the kinetic energy of natural waterfalls. The total power 
available in water when in motion depends on the weight of water 
discharged in a given time, and on the head or distance through 

1 



2 FARM MOTORS 

which the water is allowed to fall. The head of water can be 
utilized by its weight or pressure acting directly on a piston or 
on blades or paddles on wheels. 

Considering next the various forms of heat engines, work is 
accomplished by steam or gas under pressure, this pressure being 
obtained by utilizing the heat of some fuel or of the rays of the 
sun. 

A motor utilizing the heat of the sun is called a solar motor 
or a solar engine. The action of this type of motor depends on 
the vaporization of water into steam by means of the rays of 
the sun, which are concentrated and intensified by means of 
reflecting surfaces. 

In the case of the steam engine a fuel, like coal, oil, or gas, is 
burned in a furnace and its heat of combustion is utilized in 
changing water into steam, at high pressure, in a special vessel 
called a boiler. This high-pressure steam is then conveyed by 
pipes to the engine cylinder where its energy is expended in 
pushing a piston as in the case of the reciprocating engine. The 
sliding motion of the piston may be changed into rotary motion 
at the shaft by the interposition of a connecting rod and crank. 
Another method is to allow the high-pressure steam to escape 
through a nozzle, strike blades on a wheel and produce rotary 
motion direct, as in the case of the steam turbine. 

In another type of heat engine, called a hot-air engine, air is 
heated in a cylinder by a fuel which is burned outside of the en- 
gine cylinder, and by its expansion drives a piston and thus does 
work. 

In the case of gas and oil engines the fuel, which must be in a 
gaseous form as it enters the engine cylinder, is mixed with air 
in the proper proportions to form an explosive mixture. It is 
then compressed and ignited within the cylinder of the engine, 
the high pressures produced by the explosion pushing on a piston 
and doing work. These engines belong to a class called internal- 
combustion engines, and differ from the steam and hot-air 
engines, which are sometimes called external-combustion en- 
gines, in that the fuel with air is burned inside the engine cylinder, 
instead of in an auxiliary apparatus. 

The windmill derives its high pressure for doing work from the 
moving atmosphere. 



FARM MOTORS IN GENERAL 3 

The electric motor converts electrical energy at high pressure 
into work; this electrical pressure or voltage is produced in an 
apparatus called an electrical dynamo, or generator. 

Animal Motors. — The animal can be considered as a motor to 
which fuel is supplied in the form of food. This food furnishes 
energy required for the operation and maintenance of the 
various organs and processes within the animal body, as well 
as for the production of mechanical work. The animal body is, 
in fact, a combination of complex mechanisms, in every one of 
which heat is produced and work is performed. 

Comparison of Various Types of Motors. — The solar motor 
is but little used on account of its high first cost and great bulk 
in relation to the small power developed. 

In localities where the wind is abundant and little power is 
needed, the windmill is the most desirable and cheapest power. 
The greatest application of windmills is for the pumping of water 
for residences and farms, and for such other work as does not 
suffer from suspension during calm weather. Electric storage 
and lighting on a small scale from the power of a windmill has 
been tried in several places with fair success, but probably will 
not be adapted to any great extent on account of the high first 
cost of such an installation. 

The water motor or water turbine is very economical if a 
plentiful supply of water can be had at a fairly high head, but its 
reliability is affected by drought, floods and ice in the water 
supply. 

The hot-air engine, while not economical in fuel consumption, 
is well-adapted for pumping water in places where the cost of 
fuel is not an important item and where safety and simplicity of 
mechanism are essential. The hot-air engine, on account of its 
high cost, bulk and poor fuel economy, has been largely super- 
seded by the oil engine, which uses gasoline or the heavier oils. 

Of the other forms of heat engines, the internal-combustion 
engine, whether using gas or oil, is well-adapted for small and 
medium-sized powers, such as for farm use and irrigation work. 
The oil traction engine has also a very important field on the 
modern farm. 

For the generation of electricity, and in large sizes, the steam 
engines or steam turbines will be found more suitable on account 



4 FARM MOTORS 

of their lower first cost and great reliability. The steam engine 
is also used successfully on large traction engines. 

If a source of electric current is available at a low price, the 
electric motor is very desirable, as it requires little care and can 
be bought in sizes to suit all requirements. 

Of the animal motors, the horse is the most important. Unlike 
mechanical motors, the horse is self -feeding, self -reproducing 
and self -maintaining. For very short intervals, animal motors 
are capable of considerable overload capacity, but are expensive, 
require constant care and can work effectively only for short 
periods of time. With animal motors, the amount of power under 
the control of one man is much less than in the case of me- 
chanical motors. The mechanical motor requires fuel only when 
actively at work, while the animal motor requires feed at regular 
intervals whether working or not. 

Power Used on Farms. — About 25 million horses and mules 
are available for power purposes on the farms of the United 
States. This represents available animal power to the amount of 
about 16 million horsepower. The power available in mechanical 
farm motors will probably exceed 10 million horsepower. The 
total amount of power used on farms thus represents more than 
25 million horsepower, or the power which is available on farms is 
about one-third greater than the total amount of power used by 
all the manufacturing industries of this country. 

Comparative Cost of Power with Various Motors. — Varying 
character and prices of both feed for animal motors and fuel 
for mechanical motors will affect the cost of power in different 
localities. Ordinarily, the power produced by animal motors is 
more expensive than that developed by the use of mechanical 
motors. Experiments indicate that with the horse as a motor, 
the cost of power per horsepower per hour will vary from 5 
to Q}4 cts. With stationary gasoline engines, the cost of power 
will vary from 1J^ to 2}^ cts. per horsepower per hour; with 
kerosene fuel, from % to 1 ct.; with fuel oil, less than 1 ct. per 
horsepower per hour. With steam engines a horsepower per hour 
can usually be produced for about 1 ct. 

Problems: Chapter I 

1. What is a motor? Name four types of mechanical motors. 

2. Name the principal source of all energy. Explain in detail. 



FARM MOTORS IN GENERAL 5 

3. What are the fundamental principles which govern the action of vari* 
ous mechanical motors ? Illustrate how the principle is applied in the case 
of waterwheels, steam engines, gas engines, windmills, electric motors. 

4. Compare various types of mechanical motors as to their adaptability 
for use on the farm. 

5. Discuss the relative advantages and disadvantages of mechanical 
motors and of animal motors. 

6. How does the power available on American farms compare with the 
power used in the manufacturing industries of this country? 



CHAPTER II 
FUNDAMENTAL PRINCIPLES AND DEFINITIONS 

Before a study is made of any motor, the fundamental concep- 
tions of physics regarding states of matter, work, power and heat 
are essential. 

Matter. — Matter is that which occupies space and, when 
limited in amount, it is called a body. Matter in any form con- 
sists of a great many small particles, called molecules, the 
relative position of which determines the state in which a sub- 
stance exists. 

States of Matter. — Matter exists in the solid, liquid and gase- 
ous states. 

In the case of the solid the relative positions of the molecules are 
fixed. A solid having a certain shape or form, whether due to 
natural or artificial causes, will retain that form, unless and until 
it is made to change the same by some external cause. 

In the liquid, the relative positions of the various molecules 
are not fixed. The shape or form of a liquid depends, therefore, 
on the solid walls surrounding it, a liquid assuming the form of 
any vessel in which it may be placed. 

In the case of a gas the various molecules struggle to occupy 
greater space. A gas can be greatly compressed by an external 
force, and will expand to a considerable extent, if it is given perfect 
freedom. 

Motion. — Motion means change of place. If a definite amount 
of matter, called a body, is removed from one place to another, 
motion is produced. 

Force and Pressure. — Anything which produces or tends to 
produce, modifies or tends to modify motion is called force. 
Force is measured in pounds. Pressure is the intensity of force 
and is equal to the total force divided by the area over which it 
acts. For example, a force of 1,000 lb. acting on a bo.dy whose 
dimensions are 5 by 2 in., will produce a pressure or intensity 
of force equal to the force divided by the area of the body in 

square inches, or ' = 100 lb. In English and American prac- 



PRINCIPLES AND DEFINITIONS 7 

tice, pressure is always expressed in pounds per square inch. 
Thus when a steam gage on a boiler is registering 80 lb., this 
means that the steam is capable of transmitting a force of 80 lb. 
for every square inch on which it acts. If it is allowed to act on 
a 12-in. piston, the area of which is 113.1 sq. in., the total force 
exerted on the piston is 80 time's 113.1 or 9,048 lb. 

The pressure exerted by the atmosphere is called barometric 
pressure. The barometric pressure is 14.7 lb. per square inch at 
sea level and decreases as the altitude, or the height of the sur- 
face of the earth above sea level, increases. For each 2,000 ft. 
in elevation the pressure of the atmosphere is decreased by about 
1 lb. The barometric pressure plus gage pressure equals absolute 
pressure. 

Work, Energy and Power. — Work means force times distance 
through which it acts and is independent of time. If a body of 
1 lb. is raised through a distance of 1 ft., the resulting work is 
1 ft.-lb. 

The capacity for doing work is called energy. Energy exist- 
ing in a body at rest, as in the case of the raised weight, is called 
potential energy. Energy possessed by a body when in motion 
is called kinetic energy. 

As an illustration, a cubic foot of water, weighing 62.5 lb. 
when at rest at a height of 100 ft., has potential energy of 6,250 
ft.-lb. and this potential energy is changed into kinetic energy 
of work when the water is allowed to fall through that height. 
The water in the above example when allowed to fall through 10 
ft. will be capable, on account of its kinetic energy, to do 625 ft.- 
lb. of work and will have a potential energy of 6,250 — 625, or 
5,625 ft.-lb. when it comes again to rest. 

Power takes into consideration the time required to do a certain 
amount of work and is defined as the rate of doing work. Thus 
if steam at a pressure of 100 lb. moves a piston 18 in. in diameter 
through a distance of 2 ft., the work done is 100 times 508.92 
(the area of the piston in inches multiplied by the distance in 
feet) or 50,892 ft.-lb. The power of the engine, however, de- 
pends on the time that the steam requires to move the piston 
through the given distance and, if the motion is accomplished 
in 1 sec, the power of the engine is five times greater than if 
5 sec. were required. 



8 FARM MOTORS 

Horsepower. — If work is done at the rate of 33,000 ft.-lb. 
per minute, 1 hp. is said to be exerted. This means that an 
engine will have a capacity of 1 hp. if it can do 550 ft.-lb. of 
work in a second, 33,000 ft.-lb. of work in a minute, or 1,980,000 
ft.-lb. of work in an hour. To determine the horsepower de- 
veloped by any motor or engine, it is necessary to find the foot- 
pounds of work which the motor or engine is doing in a minute 
and divide this by 33,000. In the example of the previous para- 
graph if the piston passes through the distance of 2 ft. in }£o 
min.; the power of the engine in horsepower is 

25,446 X 2 = 
33,000 X-h 

It is important to remember that power takes into considera- 
tion work and time. All animals, including man, are able to 
produce more power for a short period of time, while mechanical 
motors, whether driven by water, wind, steam, gas, or electricity 
can exert, with proper care, the power for which they are designed 
for an indefinite length of time. 

Indicated Horsepower. — The term " indicated horsepower" 
(i.hp.) is applied to the rate of doing work by steam or by a gas 
in the cylinder of an engine, and is obtained by means of a 
special instrument, called an indicator. One form of this type 
of instrument, the Crosby, is shown in section in Fig. 1. It 
consists essentially of a cylinder (4), which is placed in direct 
communication with the engine cylinder, and in which moves a 
piston(8) compressing a spring above it and raising the arm (16). 
At the end of the arm is a pencil (23) which records graphically the 
pressure of the steam in the engine cylinder on the revolving 
drum (24). This drum (24) is covered with paper and receives its 
motion from the engine crosshead. From the diagram drawn 
on the drum of the indicator, the average unbalanced pressure 
is determined, and the horsepower is calculated from this and 
from dimensions and speed of the engine. 

As an illustration: Given the average unbalanced pressure of 
the steam on a 12-in. piston, as obtained by means of an indicator, 
and called the mean effective pressure, 40 lb. per square inch; 
then the total pressure exerted by the steam is 

Total pressure = 40 X 113.1 = 4,524 lb. 



PRINCIPLES AND DEFINITIONS 



9 



If the stroke of the piston is 13 in., the work done in foot-pounds 
per stroke is 

1Q 

4,524 Xj^ = 4,901 

If the engine speed is 250 r.p.m., the work per minute will be, 
if the engine is single acting, 

4,901 X 250 = 1,225,250 ft. -lb. 




Fig. 1. — Steam engine indicator. 

Since 33,000 ft. -lb. per minute is 1 hp., the power of the engine 
when single-acting is 

1,225,250 



33,000 



= 37.1 i.hp. 



As steam engines are usually double-acting, an indicator card 
would have to be taken of the crank end, the unbalanced or the 
mean effective pressure determined for that end and the indicated 
horsepower calculated by the above method, taking into considera- 
tion the size of the piston rod. The total indicated horsepower 
of the engine is the sum of that calculated for the two ends. 



10 



FARM MOTORS 



Brake Horsepower. — Brake horsepower represents the actual 
effective power which a motor or engine can deliver for the pur- 
pose of work at a shaft or a brake, or transmit to a belt for 
stationary work, such as threshing or the driving of machines. 
An instrument for the measurement of the brake horsepower of 
motors, and called a Prony brake, is shown in Fig. 2. This brake 
consists of two wooden blocks BB which fit around the pulley P 




//////////////M////////////////////////^///// 



Fig. 2. — Prony brake. 

and are tightened by means of the thumb nuts NN. A projec- 
tion of one of the blocks, the lever L, rests on the platform scale 
S. When the brake is balanced, the power absorbed is measured 
by the weight as registered on the scales, multiplied by the 
distance it would pass through in that time if free to move. If 
I is the length of the brake arm in feet, w the weight as registered 
on the scales, in pounds, and n the revolutions per minute of 
the motor, the horsepower absorbed can be calculated by the 
formula 

2wlwn 
Brake horsepower = ~» ~~~ 

As an illustration, the scale reading of an engine running at 250 
r.p.m. is 80 lb. If the length of the brake arm is 5)4 ft., calculate 
the brake horsepower developed. 

« , , 2 X 3.1416 X 5.25 X 80 X 250 OA An 
Brake horsepower = »» ~~~ = 20.00 

Drawbar Horsepower. — The belt or the brake horsepower 
minus the power required to propel the weight of a traction engine 



PRINCIPLES AND DEFINITIONS 11 

or power vehicle is called the drawbar horsepower. Ordinarily, 
a traction engine will require about 50 per cent, of the total 
power developed by its motor, to move the traction engine. This 
means that the drawbar horsepower, available for plowing or for 
pulling implements, is about one-half of the total power developed 
by the motor. 

Nature of Heat. — Heat is a form of energy and not a material 
substance. The heat of a body depends on the vibratory motion 
of the particles or molecules of which the body is built up; the 
greater the rate of motion of these molecules the higher is the 
temperature of the body. 

Temperature. — Temperature indicates the relative heats of 
bodies, or the relative rates of motion of the molecules in bodies. 
Temperature is not a measure of the amount or quantity of 
heat in a body. Thus a small and a large piece of metal may be 
heated to the same temperature, but the large piece would 
possess the greater quantity of heat. Temperature is an indica- 
tion of the sensible heat of a substance, or the heat intensity 
which can be revealed to the senses of an observer. 

Thermometers. — A thermometer is an instrument by means of 
which the temperature of a substance is measured. As usually 
constructed, it consists of a liquid such as mercury or alcohol 
inclosed in a bulb at one end of a thin glass tube, the temperature 
changes producing sufficient variations in the expansion of the 
liquid to be read off on a scale attached to, or graduated on, the 
glass tube. 

Thermometers are graduated in three different ways, which are 
called the three thermometric scales, the type of scale depending 
on the number of graduations, or degrees (° denotes degree), 
between the melting-point of ice and the boiling-point of water. 

The scale mostly used in English-speaking countries is the 
Fahrenheit (F.). In this case the melting-point of ice is taken 
at 32° and the boiling-point of water at 212°. Thus the Fahren- 
heit degree (°F.) is }{ go of the interval between the two fixed 
points. 

In scientific work the Centigrade scale is used in most countries. 
The Centigrade degree is Jloo of the temperature interval 
between the melting-point of ice and the boiling-point of water, 
these two fixed points being denoted 0°C. and 100°C. respectively. 



12 FARM MOTORS 

Another scale, used only to a limited extent in certain countries 
of Europe is the Reaumur scale, which has the melting-point of 
ice at 0°R. and the boiling-point of water at 80°R. 

The relations existing between the thermometric scales mostly 
used, i.e., the Fahrenheit (F.) and the Centigrade (C), can be 
expressed : 

degrees C. = % (degrees F. —32) 
degrees F. = % degrees C. +32 
Example: Convert 15°C. to the Fahrenheit scale and 400°F. 
to the Centigrade scale. 

degrees F. = % X degrees C. +32 
= % X 15 + 32 
= 27 + 32 = 59°F. 
degrees C. = % (degrees F. —32) 
= % (400 - 32) 
= 204°C. 
Table 1 can be used for converting Centigrade into Fahrenheit 
degrees and conversely. 

Units of Heat. — Heat is measured in heat units. A heat unit 
is the amount of heat required to raise the temperature of 1 
lb. of water 1°. The heat unit used in English-speaking countries 
is the British thermal unit (B.t.u.). The B.t.u. is defined as the 
amount of heat required to raise 1 lb. of water from 62°F. to 
63°F. 

When a certain illuminating gas is said to contain 600 B.t.u., 
this means that each cubic foot of the gas is capable of raising 
the temperature of 10 lb. of water through 60°F., or that it will 
raise the temperature of water so that the product of the weight 
of water and temperature rise (in °F.) is 600. 

Mechanical Equivalent of Heat. — It has been proven experi- 
mentally that heat and work are mutually convertible. It re- 
quires 778 ft.-lb. of work to produce 1 B.t.u. ; and similarly 1 B.t.u. 
will produce 778 ft.-lb. of work, if all the heat is converted into 
work. The number 778 is called the mechanical equivalent of 
heat. It is due to the fact that heat can be converted into work 
that the various heat engines, including the steam, gas and oil 
engines, are possible. 

Specific Heat. — As the addition of the same quantity of heat 
will not produce the same temperature changes in equal weights 



PRINCIPLES, AND DEFINITIONS 



13 



Table 1. — Relation Between the Fahrenheit and Centigrade Ther- 
mometry Scales 



Fahr, 


' Cent. 


Fahr. 


Cent. • 


-30 


-34.4 


210 


98.9 


-20 


-28.9 


212 


100.0 


-10 


-23.3 


220 


104.4 





-17.8 


230 


110.0 


+ 10 


-12.2 


240 


119.6 


20 


- 6.7 


250 


121.1 


30 


- 1.1 


260 


126.7 


32 


0.0 


270 


132.2 


40 


+ 4.4 


280 


137.8 


50 


10.0 


290 


143.3 


60 


15.6 


300 


148.9 


70 


21.1 


310 


154.4 


80 


26.7 


320 


160.0 


90 


32.2 


330 


165.6 


100 


37.8 


340 


171.1 


110 


43.3 


350 


176.7 


120 


48.9 


360 


182.2 


130 


54.4 


370 


187.8 


140 


60.0 


380 


193.3 


150 


65.6 


390 


198.9 


160 


71.1 


400 


204.4 


170 


76.7 


410 


210.0 


180 


82.2 


420 


215.6 


190 


87.8 


430 


221.1 


200 


93.3 


440 


226.7 



of different substances, it is evident that the amount of heat 
which can be taken in or given out by any substance depends on 
the capacity of that substance for heat. The capacity of a sub- 
stance for heat, or the resistance which a substance offers to a 
change in its temperature, is called its specific heat. The 
specific heat of water is taken as the standard and equal to one. 
Specific Gravity. — By specific gravity is meant the relation 
existing between the weight of any substance and the weight of 
an equal volume or bulk of water. Thus the specific gravity 
of cast iron is about 7, which means that a cubic foot of iron is 
seven times heavier than a cubic foot of water. In Table 2 
are given the specific heats and specific gravities of common 
substances. 



14 



FARM MOTORS 



Table 2. — Specific Heats and Specific Gravities of Common 

Substances 



Name of substance 



Specific heat 
(average) 



Specific gravity 
(average) 



Solids 

Iron, cast 

Iron, wrought 

Steel 

Lead 

Copper 

Glass 

Ice 

Stone 

Brickwork, masonry. . 

Liquids 

Water 

Kerosene 

Gasoline '. 

Alcohol, ethyl 

Alcohol, methyl 

Ammonia 

Vegetable oil 

Gases 

Air 

Oxygen 

Hydrogen 

Nitrogen 

Ammonia 



0.1298 
0.1138 
0.1170 
0.0314 
0.0951 
0.1700 
0.5040 
0.2100 
0.2000 



1 . 0000 
0.4750 
0.5350 
. 5500 
0.5900 

0.4000 



0.2375 
0.2175 
3 . 4090 
0.2438 
0.5080 



7.2100 
7.7000 
7 . 8000 
11.4000 
8.9000 
2.6000 
0.9000 
2 . 7500 
2 . 0000 



1 . 0000 
0.8100 
0.6900 
0.7900 
0.8080 
0.9500 
0.9000 



1 . 0000 
1 . 1052 
0.0692 
0.9701 

0.5889 



Problems : Chapter II 

1. Calculate the work done by a pump when lifting 100 gal. of water 
to a height of 125 ft. 

2. The pressure of steam on the piston of an engine is 30 lb. per square 
inch. If the diameter of the piston is 18 in., its stroke 2 ft., how much 
work does the engine do per hour if its speed is 110 r.p.m.? 

3. Calculate the horsepower of the engine in the above problem. 

4. Why will two horses be able to draw a heavy load up a hill when a 
40-hp. automobile will be unable to do so? Explain the reason in detail. 

5. Calculate the horsepower of a traction engine required to draw a plow 
at the rate of 2 miles per hour if the pull on the drawbar is 15,000 lb. 

6. Convert the following readings in degrees Centigrade to the Fahren- 
heit scale: 

- 18, - 2, 15, 53, 78. 



PRINCIPLES AND DEFINITIONS 15 

7. Convert, the following readings of the Fahrenheit scale to degrees 
Centigrade : 

- 20, 10, 60, 80, 220, 350. 

8. A pound of gasoline will yield, when completely burned, 19,200 heat 
units; calculate the foot-pounds of energy contained. 

9. Calculate the heat required to raise the temperature of 1 lb. of cast 
iron, of copper, of glass, of stone and of water through 100 C F. 

10. Calculate and compare the weights of a gallon of kerosene, of gasoline, 
of ethyl alcohol, of ammonia and of water. 

11. Calculate the indicated horsepower of an engine having the following 
dimensions : 

Diameter of cylinder 16 in. 

Diameter of piston rod '. 2 J^ in. 

Stroke 24 in. 

Revolutions per minute 120 

Mean effective pressure, head end 52.3 

Mean effective pressure, crank end 52.0 

12. A gasoline engine running at 300 r.p.m. is tested by means of a 
Prony brake. If the length of the brake arm is 42 in. and the net weight 
as registered on the platform scales is 35 lb., calculate the brake horsepower 
developed by the engine. 



CHAPTER III 
STEAM GENERATION AND STEAM BOILERS 

Theory of Steam Generation. — If heat is added to ice, the 
effect will be to raise its temperature until the thermometer 
indicates 32°F. When this point is reached, a further addition 
of heat does not produce an increase in temperature until all the 
ice is changed into water, or in other words the ice melts. It has 
been found experimentally that 144 B.t.u. are required to change 
1 lb. of ice into water. This quantity is called the latent heat 
of liquefaction of ice. 

After the quantity of ice given, which for simplicity may be 
taken as 1 lb., has all been turned into water, it will be found that 
if more heat is added the temperature of the water will again 
increase, though not as rapidly as did that of the ice. While 
the addition of each British thermal unit increases the tempera- 
ture of ice 2°F., in the case of water an increase of only about 1° 
will be noticed for each British thermal unit of heat added. 
This difference is due to the fact that the specific heat, or resist- 
ance offered by ice to a change in temperature is one-half that 
offered by water. That is, the specific heat of ice is 0.5. 

If the water is heated in a vessel open to the atmosphere, its 
temperature will keep on going up until about 212°F., the boiling- 
point of water, when further addition of heat will not produce 
any temperature changes, but steam will issue from the vessel. 
It has been found that about 970 B.t.u. will be required to change 
1 lb. of water at atmospheric pressure and at 212°F. into steam. 
The quantity of heat so supplied which changes the physical 
state of water from the liquid state to steam is called the latent 
heat of vaporization. 

If the above operations are performed in a closed vessel, water 

will boil at a higher temperature than 212°F., since the steam 

driven off cannot escape and is compressed, raising the pressure 

and consequently the temperature. The latter is the condition 

in an ordinary steam boiler. 

16 



STEAM GENERATION AND STEAM BOILERS 17 

That the boiling-point of water depends on the pressure is 
well known. Thus in a place in Colorado where the altitude is 
6,000 ft. above sea level and the barometric pressure is 12.6 lb. 
per square inch the boiling-point of water is about 204°F. as 
compared with 212°F. at sea level where the barometric pressure 
is 14.7 lb. per square inch. 

As the pressure is increased to 60 lb. per square inch by the 
gage, it will be found that the boiling-point of water is 275°F. 
At 100 lb. per square inch water will boil at 317°F. and at 150 lb. 
the temperature will read 350. 5°F. before steam will be formed. 

Steam is spoken of as being in three conditions : 

1. Wet. 

2. Dry. 

3. Superheated. 

In the first case the steam carries with it a certain amount of 
water which has not been evaporated. The percentage of this 
water determines the condition of the steam; that is, if there is 
3 per cent., by weight, of moisture, the steam is spoken of as being 
97 per cent. dry. A stationary boiler, properly erected and oper- 
ated and of suitable size, should generate steam that is 98 per 
cent. dry. If there is more than 3 per cent, moisture, there is 
every reason to believe that the boiler is improperly installed, 
inefficiently operated, or is too small for the work to be done. 

In the second condition, that of dry steam, the vapor carries 
with it no water that has not been evaporated; that is, it is dry. 
Any loss of heat, however small, not accompanied by a correspond- 
ing reduction in pressure, will cause condensation, and wet steam 
will be the result. Steam, whether wet or dry, has a definite 
temperature corresponding to its pressure. 

An increase in temperature not accompanied by an increase in 
pressure will cause the steam to acquire a condition that will 
permit a loss of heat at constant pressure without condensation 
necessarily following. This third condition is called superheat. 
The advantage of superheated steam lies in the fact that its 
temperature may be reduced by the amount of the superheat 
without causing condensation. This makes it possible to trans- 
mit the steam through mains and still have it dry and saturated 
at the time it reaches the engine cylinder. Superheated steam 
may be secured by passing saturated steam through coils of pipe 



18 



FARM MOTORS 



in the path of the hot flue gases from the boiler to the chimney. 
An apparatus for superheating steam is called a superheater. 

The pressure of steam will remain constant if it is used as fast 
as it is generated. If an engine uses steam too rapidly the boiler 
pressure will drop and similarly if the fuel is burned at a constant 
rate and an insufficient amount of steam is used the pressure of 
the steam in the boiler will increase. 

In Table 3 are given some of the most important properties of 
saturated steam, which include: 

1. Pressure of steam in pounds per square inch absolute. 



Table 3. — Properties of Saturated Steam 
English Units 

















Abs. 


Abs. pres- 
sure, 
pounds 

per sq. in. 


Vaporiza- 
tion tem- 
perature, 
degrees F. 


Heat 
of the 
liquid 


Latent 
heat 
of evapo- 
ration 


Total 

heat 

of steam 


Specific 

volume, 

cubic feet 

per lb. 


Density, 

pounds 

per cu. ft. 


pres- 
sure, 

pounds 
per 

sq. in. 


1 


101.8 


69.8 


1,034.6 


1,104.4 


333.00 


0.00300 


1 


2 


126.1 


94.1 


1,021.4 


1,115.5 


173.30 


0.00577 


2 


3 


141.5 


109.5 


1,012.3 


1,121.8 


118.50 


. 00845 


3 


4 


153.0 


120.9 


1,005.6 


1,126.5 


. 90.50 


0.01106 


4 


5 


162.3 


130.2 


1,000.2 


1,130.4 


73.33 


0.01364 


5 


6 


170.1 


138.0 


995.7 


1,133.7 


61.89 


0.01616 


6 


7 


176.8 


144.8 


991.6 


1,136.4 


53.58 


0.01867 


7 


8 


182.9 


150.8 


988.0 


1,138.8 


47.27 


0.02115 


8 


9 


188.3 


156.3 


984.8 


1,141.1 


42.36 


0.02361 


9 


10 


193.2 


161.2 


981.7 


1,142.9 


38.38 


0.02606 


10 


14.7 


212.0 


180.1 


970.0 


1,150.1 


26.79 


0.03733 


14.7 


20 


228.0 


196.2 


959.7 


1,155.9 


20.08 


0.04980 


20 


30 


250.3 


218.9 


944.8 


1,163.7 


13.74 


0.07280 


30 


40 


267.3 


236.2 


933.0 


1,169.2 


10.49 


0.09530 


40 


50 


281.0 


250.2 


923.2 


1,173.4 


8.51 


0.11750 


50 


60 


292.7 


262.2 


914.6 


1,176.8 


7.17 


0.13940 


60 


70 


302.9 


272.7 


906.9 


1,179.6 


6.20 


0.16120 


70 


80 


312.0 


282.1 


900.1 


1,182.2 


5.47 


0.18290 


80 


90 


320.3 


290.6 


893.7 


1,184.3 


4.89 


0.20450 


90 


100 


327.8 


298.4 


887.8 


1,186.2 


4.430 


0.22570 


100 


125 


344.4 


315.5 


874.6 


1,190.1 


3.582 


0.27920 


125 


150 


358.5 


330.1 


863.1 


1,193.2 


3.013 


0.33190 


150 


200 


381.9 


354.6 


843.3 


1,197.9 


2.289 


0.43700 


200 


250 


401.1 


374.7 


826.6 


1,201.3 


1.848 


0.54100 


250 


300 


417.5 


392.0 


811.8 


1,203.8 


1.547 


0.64700 


300 



STEAM GENERATION AND STEAM BOILERS 19 

2. Temperatures of steam in degrees Fahrenheit. This column 
of temperatures shows the vaporization temperature at each of 
the given pressures. 

3. Heat of the liquid, or the heat required to bring up a 
pound of water from freezing-point to boiling-point. 

4. The latent heat, or the heat required to vaporize a pound 
of water at the given pressure after boiling-point is reached. 

5. The volume of 1 lb. of steam at the various pressures. 

6. Density of steam in pounds per cubic foot. 

Fuels. — The fuels most commonly used for steam generation 
are coal, wood, petroleum . oils and natural gas. The combus- 
tible, or heat-producing, constituents of all fuels are carbon and 
hydrogen. A fuel containing much sulphur should be avoided 
for steam generation on account of the injurious sulphurous acid 
formed when the fuel is burned. 

Wood is but little used for steam generation except in remote 
places, where timber is plentiful or in special cases where sawdust, 
shavings and pieces of wood are by-products of manufacturing 
operations. Wood burns rapidly and with a bright flame, but 
does not evolve much heat. When first cut, wood contains 30 to 
50 per cent, of moisture, which can be reduced by drying to about 
15 per cent. One pound of dry wood is equal in heat-producing 
value to ^fo lb- of soft coal. It is important that wood be dry, 
as each 10 per cent, of moisture reduces its heat-producing value 
as a fuel by about 12 per cent. 

Coal is more extensively used as a fuel for steam generation 
than any other substance. All coals are derived from vegetable 
origin and are classified as follows: 

1. Anthracite, or hard coal, consisting mainly of carbon. 
This coal is slow to ignite, burns with very little flame, produces 
and gives off very little smoke. Anthracite coal contains very 
little volatile matter and may contain none. 

2. Semianthracite coal is softer and lighter than anthracite, 
and contains less carbon and from 7 to 12 per cent, volatile matter. 

3. Semibituminous, which contains from 12 to 25 per cent, 
volatile matter and less fixed carbon than the semianthracite. 

4. Bituminous, or soft, coal contains more than 20 per cent, 
of volatile matter and only about 50 per cent, of fixed carbon. 

5. Lignite, which may be classified as soft coal arrested in the 



20 FARM MOTORS 

process of formation. This coal contains a very large proportion 
of volatile matter and less than 50 per cent, fixed carbon. How- 
ever, it has a good heating value and is usually a free burner, 
but owing to the high percentage of volatile matter it will not 
stand storage, but crumbles badly soon after exposure to air. 

Other solid fuels used to some extent for steam generation are : 
Peat, which is an intermediate between wood and coal and found 
in bogs; sawdust, oak bark after it has been used in the process 
of tanning, bagasse or the refuse of cane sugar, and cotton 
stalks. Coke is also used to some extent, the advantage of this 
fuel as compared with coal being that coke will not ignite spon- 
taneously, will not deteriorate or decompose when exposed to 
the atmosphere, and produces no smoke when burned. Coke is 
manufactured by burning coal in a limited air supply, the volatile 
hydrocarbons being driven off during the process. 

Petroleum fuels, either in the form of crude petroleum or as 
the refuse left from its distillation, are used for making steam to 
a considerable extent in certain parts where the relative cost of 
oil is less than that of coal. It has been estimated that petro- 
leum oils at 2 cts. per gallon are equally economical for steam 
making as coal at $3 per ton. The advantages of oil as com- 
pared with solid fuels are ease of handling, cleanliness and 
absence of smoke after combustion. 

Natural gas is used for steam generation where its cost is low. 
If the cost of natural gas is greater than 10 cts. per 1,000 cu. ft. 
it cannot compete with coal at $3 a ton. Illuminating gas is too 
ex*pensive for steam generation and cannot compete with other 
fuels. 

Combustion. — Combustion is a chemical combination of the 
heat-producing constituents of a fuel with oxygen and is accom- 
panied by the production of heat and light. The supply of oxy- 
gen for combustion is taken from the atmosphere, every pound 
of air consisting of 0.23 part by weight of oxygen and 0.77 part 
by weight of nitrogen. 

It has been found that most coals require between 11 and 12 
lb. of air for every pound of coal burned and that the heat de- 
veloped during the combustion of 1 lb. of the various fuels is as 
follows : 



STEAM GENERATION AND STEAM BOILERS 21 
Table 4. — Heat Developed by the Combustion of Various Fuels 



Name of fuel 


Heat developed in B.t.u. 
per pound of fuel 


Heat developed in B.t.u. 
per cubic foot of fuel 


Anthracite coal 


13,200 to 13,900 

13,000 to 16,000 

12,000 to 15,000 
8,500 to 11,400 
8,000 to 11,000 
8,200 to 9,200 

18,000 to 20,000 

18,550 

19,000 

11,500 




Semibituminous coal 




Bituminous coal 




Lignite 




Peat (dry) 




Wood 




Petroleum fuels 




Kerosene 




Gasoline 




Alcohol (100 per cent.) 

Natural gas 


900 to 1,000 
600 to 700 


Illuminating gas 




Producer gas 




100 to 150 









Commercial Value of Fuels. — In the furnace of the actual 
boiler plant only 30 to 70 per cent, of the heat units contained 
in the given fuel is utilized for the generation of steam. The 
principal losses in the boiler furnace are due to incomplete com- 
bustion, infiltration of air through setting, and to the heat carried 
away in the flue gases. The methods to be employed in order to 
reduce these losses to a minimum will be discussed under boiler 
management. 



STEAM BOILERS AND AUXILIARIES 

Principal Parts of a Steam Power Plant. — The principal parts 
of a steam power plant are illustrated in Fig. 3, and include the 
following : 

A furnace in which the fuel is burned. This consists of a 
chamber arranged with a grate (1), if coal or any other solid fuel 
is used, and with burners when the fuel is in the liquid or gaseous 
state. The furnace is connected through a flue or breeching (2) 
to a chimney. The function of a chimney is to produce suffi- 
cient draft, so that the fuel will have the proper amount of air 
for combustion; it also serves to carry off the obnoxious gases 
after the combustion process is completed. The flue leading to 



22 



FARM MOTORS 



the chimney is provided with a damper (3), so that the intensity 
of the draft can be regulated. 

A boiler (4), which is a closed metallic vessel filled to about two- 
thirds of its volume with water. The heat developed by burning 
the fuel in the furnace is utilized in converting the water con- 
tained in the boiler into steam. The boiler (4) is arranged with 
a water column (5) to show the water level, with a safety valve (6) 
to prevent the pressure from rising too high, and with a gage (7) 
to indicate the steam pressure. 




Fig. 3. — Steam power plant. 

The function of a setting is to provide correct spaces for the 
furnace, combustion chamber and ashpit, to support the boiler 
shell, to prevent air from entering the furnace above the fuel 
bed, and to decrease the heat radiation to a minimum. 

The feed pump (8) supplies the boiler with water through the 
feed pipe (9). 

The steam lines (10) and (11) convey steam from the boiler to 
the engine and to the steam end of the pump respetivecly. 



STEAM GENERATION AND STEAM BOILERS 23 

In the engine the energy of the steam is expended in doing 
work. The steam enters the engine cylinder (12) through the valve 
(13) and pushes on the piston(14). The sliding motion of the pis- 
ton, which is transmitted to the piston rod (15), is changed into 
rotary motion at the shaft(16) by means of a connecting rod(17) 
and crank (18). 

The exhaust pipe (19) conveys the used steam to the atmo- 
sphere, to the condenser, or to some use where its heat is ab- 
stracted, converting the steam back into water. 

Classification of Boilers. — Boilers are divided into fire-tube 
and water-tube types. In the fire-tube the hot gases developed 
by the combustion of the fuel pass through the tubes, while 
in the water-tube boilers these gases pass around the tubes. 
Either type may be constructed as a vertical or as a horizontal 
boiler, depending on whether the axis of the shell is vertical or 
horizontal. 

The fire-tube boiler may be externally or internally fired. 
In the externally fired boiler the furnace is in the brick setting 
entirely outside of the boiler shell, while in the internally fired 
types the furnace is in the boiler shell, no brick setting being 
necessary. For stationary work the externally fired boiler is 
most common, while the internally fired types are always used 
for locomotive and traction engine purposes and generally for 
marine use. Vertical fire-tube boilers are usually internally 
fired. 

Return Tubular Boiler. — Boilers of this type are most com- 
monly used in this country. The general appearance of a re- 
turn tubular boiler is shown in Fig. 4. Fig 5 illustrates the de- 
tails of the setting. The height of the boiler above the grate 
depends upon the fuel employed. 

These boilers as seen from the cuts consist of a cylindrical 
shell closed at the end by two flat heads, and of numerous small 
tubes which extend the whole length of the shell. Two-thirds 
of the volume of the shell is filled with water, the remaining part 
being left for the disengagement of the steam from the water, 
and called the steam space. Sometimes, as shown in Fig. 6, a 
steam dome D is provided to increase the volume of the steam 
space. The coal burns upon the grates which, as shown in Fig. 
5, rest upon the bridge-wall W and upon the front of the setting. 



24 



FARM MOTORS 




'MMM^M^M^^^^^m /fSv^% ! o°:iP 



?7> 



Fig. 4. — Return tubular boiler. 




Fig. 5. — Details of boiler setting. 




Fig. 6. — Boiler with dome. 



STEAM GENERATION AND STEAM BOILERS 25 

The gases pass from the furnace under and along the boiler shell 
to the back connection or combustion chamber C, and from 
there to the front through the tubes and up the uptake to the 
breeching or flue which leads to the chimney. 

Vertical Fire-tube Boilers. — Two forms of vertical boilers are 
shown in Figs. 7 and 8. In the form shown in Fig. 7 the tops 



^~_ 




ill! 

hi 

■1 ill 




1 JLdJdl& 


jB 




Fig. 7. — Vertical boiler. 
Exposed tube type. 



Fig. 8. — Vertical boiler. 

Submerged tube type. 



of the tubes are above the water line and may become overheated 
when the boiler is forced. To prevent injury from this cause, 
some forms of vertical boilers are constructed as shown in Fig. 8, 
the tops of the tubes being ended in a submerged tube-sheet 
which is kept below the water line. 

The essential parts of all forms of vertical boilers are a cylin- 



26 FARM MOTORS 

drical shell with a firebox and ashpit in the lower end. The 
tubes lead directly from the furnace to the upper head of the 
shell. The hot gases from the furnace pass through the tubes 
and out of the stack. 

Vertical boilers occupy little floor space and require no setting 
or foundation. They can also be used as portable boilers. 

Water-tube Boilers. — Water-tube boilers are used in large 
power plants on account of their adaptability to higher pressures 
and larger sizes, decreased danger from serious explosions, 
greater space economy, and rapidity of steam generation. For 
small power plants the fire-tube boiler is usually more suitable 
on account of its lower first cost. Also in a fire-tube boiler if a 
tube should break, the boiler can be repaired by plugging without 
interrupting service, which is not the case with most types of 
water-tube boilers. As far as economy is concerned, numerous 
tests show that either type when properly designed and operated 
will give the same economy. 

There are many different types of water-tube boilers on the 
market, but the essential parts of all are tubes filled with water 
and one or more drums for the disengagement of the steam from 
the water. 




(b) 
Fig. 9. — Grate bars. 

Grates for Boiler Furnaces. — Grates are formed of cast-iron 
bars. Several forms of grate bars are illustrated in Figs. 9 and 
10. Plain grates (b), Fig. 9, are best adapted for caking coals 
and are usually provided with iron bars cast in pairs and lugs 
at the side. The Tupper type of grate (c), Fig. 9, is more suitable 
for the burning of hard coal, which does not cake. The grates 
of a boiler furnace can be easily interchanged to suit the fuel 
burned. For most economical results some form of rocking and 
dumping grate, as shown in Fig. 10, should be used. 

Piping for Boilers. — Pipes used for carrying steam are made of 
wrought iron or of steel. Wrought-iron pipe is superior to steel 



STEAM GENERATION AND STEAM BOILERS 27 

pipe as far as durability is concerned, but is more expensive and 
more difficult to secure. Sizes of pipe are named by the 
inside diameter, while boiler tubes go by the outside diameter. 

1, 



Standard steam pipe is made in sizes of }£, 34, %>. 



M: 



4, 



1J4, iy 2 , 2, 2H, 3, 3K, 4, Q/ 2 , 5, 6, 7, 8, 9, 10, 11 and 12 in. 
Sizes above 12 in. are named by the outside diameter. 

The various grades of pipe are merchant, standard, extra 
heavy and double extra heavy. Merchant pipe is somewhat 




Fig. 10. — Dumping grate. 



lighter than standard pipe and its manufacture is being discon- 
tinued. Extra heavy and double extra heavy have the same out- 
side diameters as standard pipe, but the inside diameters are 
smaller, due to the greater thickness of the pipe. 

Steam pipe lines should always be laid with a gradual inclina- 
tion downward, so as to allow the condensation that occurs to 
flow in the direction in which the steam is moving. If this is 
not done water may accumulate, will be picked up by the steam 
and may cause much damage by water-hammer. 

Pipe Fittings. — Fig. 11 illustrates several forms of pipe unions, 
which are used for uniting two lengths of pipe. 

The elbow or ell shown in Fig. 12 is employed for connecting 
two pipes of the same size and at an angle to each other. If 
the pipes are of different diameters a reducing ell as shown in 
Fig. 13 should be used. 

The tee shown in Fig. 14 is used for making a branch at right 
angles to a pipe line. 

The cross shown in Fig. 15 is used when two branches must be 
made in opposite directions. 

In order to reduce the size of a pipe line a bushing, Fig. 16, or 
a reducer, Fig. 17, can be used. 

To close the end of a pipe a cap, Fig. 18, is used, while the plug 



28 



FARM MOTORS 



shown in Fig. 19 is used to close a pipe threaded on the inside or 
to close a fitting. 





Pig. 11. — Pipe unions. 




Fig. 13.— Reducing Ell. 



Fig. 14.— Tees. 






Fig. 15. — Cross. Fig. 16. — Bushing. Fig. 17. — Reducer. 




Fig. 18.— Cap. Fig. 19.— Plug. 

Valves. — The function of a valve is to control and regulate the 
flow of water, steam, or gas in a pipe. In the globe valve in Fig. 



STEAM GENERATION AND STEAM BOILERS 29 

20 the fluid usually enters at the right, passes under the valve and 
out at the left. 

This method of installation places the pressure of the steam, or 
other fluid, against the disc in such a way that it tends to open the 
valve. The advantages claimed for this method are: 






Fig. 20.— Globe valve. Fig. 21.— Gate valve. Fig. 22.— Angle valve 

1. When the valve is closed the stem may be packed without 
cutting the steam pressure off the entire line. 

2. The adjustment of the opening can be made more accu- 
rately against the steam pressure than with it. 

3. The flow of steam 
tends to keep the valve 
seat free from scale and 
other dirt. 

Those who favor the 
other method claim, as 
the principal advantage, 
that the pressure of the 
steam, when the valve is closed, tends to keep it in that position 
and that there is much less likelihood of the valve leaking. Both 
methods will be found in use, but it is probable that a large 
majority of the installations will be found to be in accordance 
with the first method. 

A gate valve is shown in Fig. 21. This form of valve gives a 




Fig. 23.— Check valve. 



30 



FARM MOTORS 



straight passage through the valve, and is preferable for most 
purposes to the globe valve. 

Fig. 22 illustrates an angle valve which takes the place of 
an ordinary valve and ell. 

The function of a check valve illustrated in Fig. 23 is to allow 
water or steam to pass in one direction but not in the other. 

A boiler feed line should always be provided with a check valve 
and also with some form of globe or gate valve to enable the 
operator to examine and repair the check valve. 

Safety Valves. — The function of a safety valve is to prevent 
the steam pressure from rising to a dangerous point. The two 





Fig. 24. — Lever safety valve. 



Fig. 25. — Pop safety valve. 



common forms of safety valves are the lever safety valve and the 
spring or pop safety valve. 

The lever safety valve shown in Fig. 24 consists of a valve disc 
which is held down on the valve seat by means of a weight acting 
through a lever, the steam pressing against the bottom of the 
disc. The lever is pivoted at one end to the valve casing and is 
marked at a number of points with the pressure at which the 
boiler will blow off if the weight is placed at that particular point. 

The pop safety valve shown in Fig. 25 differs from the lever 
valve in that the valve disc is held on its seat and the steam pres- 
sure is resisted by a spring in place of a weight and lever. Pop 
safety valves can be adjusted to blow off at various pressures by 
tightening or loosening the spring pressure on the valve disc. 



STEAM GENERATION AND STEAM BOILERS 31 



Steam Gages. — A steam gage indicates the pressure of the 
steam in a boiler. The most common form, shown in Fig. 26, 
consists of a curved spring tube closed at one end and filled 




Fig. 26. — Steam gages. 

with some liquid. One end of the tube is free, while the other is 

fastened to the fitting which is secured into the space where 

the pressure is to be measured. Pressure applied to the inside 

of the tube causes the free end to 

move. This motion is communicated 

by means of levers and small gears 

to the needle which moves over a 

graduated dial face, and records the 

pressure directly in pounds per square 

inch. 

Water Glass and Gage Cocks. — The 
height of the water level in a boiler is 
indicated by a water glass, one end of 
which is connected to the steam space 
and the other end to the water space in 
the boiler. All boilers should also be 
provided with three gage cocks, one of 
which is set at the desired water level, 
one above it and one below. These 
are more reliable than the water glass 
and should be used for checking the 
glass. 

Water Column. — The steam gage, water glass and gage cocks 
are usually fastened to a casting called a water column. One 
form of water column is shown in Fig. 27, this also being fitted 




Fig. 27. — Water column. 



32 



FARM MOTORS 



with a float and whistle to notify the operator should the water 
in the boiler become too low or too high. A fireman who takes 
proper care of the boilers in his charge will never allow the water 
to be at a height that will necessitate audible warning. 

Steam Traps. — The object of a steam trap is to drain the water 
from pipe lines without allowing the steam to escape. One form 

of steam trap is 
shown in Fig. 28, the 
valve being controlled 
by a float when the 
water in the trap rises 
to a sufficient height. 
Feed Pumps and 
Injectors. — Water is 
forced into steam 
boilers by pumps or 
injectors. A pump 
will handle water at 
any temperature, 



By-Pass 




Fig. 28. — Steam trap. 



while an injector can be used only when the water is cold. 
The injector is not as wasteful of steam as a pump and for 
feeding cold water to a boiler has the additional advantage, 
that it heats the water while feeding it to the boiler. 

Feed pumps may be driven from the crosshead of an engine, 
as is often the case on traction engines. Such pumps are very 
simple, but can only supply water to the boiler when the engine 
is in operation. 

Direct-acting steam pumps, driven by their own steam cyl- 
inders, are most commonly used for feeding stationary boilers, 
as they can be operated independently of the main engine and 
their speed can be regulated to suit the feed water demand of 
the boilers. 

The details of construction of two forms of direct-acting pumps 
are shown in Figs. 29 and 30. 

In the pump shown in Fig. 29, 1 is the steam cylinder and 2 
is the water cylinder. The valve E is moved by the vibrating 
arm F and admits steam into the cylinder 1. If steam is ad- 
mitted at the left of the piston A , the piston will be moved to the 
right, pushing the plunger B, driving the water through the 



STEAM GENERATION AND STEAM BOILERS 33 




///////////^^^ 




Fig. 29. — Boiler feed pumps. t 



34 



FARM MOTORS 



water valve K, and into the feed line at 0. While the plunger 
is moving to the right, a partial vacuum is formed at its left, 
which opens the valve N and draws the water from the supply 
at C. When the plunger B reaches the extreme position to the 
right, the vibrating arm F moves the valve E to the left, admit- 
ting steam which pushes the piston and plunger to the left, driv- 
ing the water through the valve L and taking a new supply 
through M. The function of the air chamber P is to secure a 




Fig. 30. — Boiler feed pump. 



steady flow of water through the discharge and to prevent 
shock in the piping. 

The pump shown in Fig. 30 differs from the one just described 
in that the steam valve G is operated by the steam in the steam 
chest and not by a vibrating arm outside of the cylinder. The 
piston C is driven by steam admitted under the slide valve G, this 
valve being moved by a plunger F. This plunger F is hollow at 
the ends and the space between it and the head of the steam chest 
is filled with steam. Thus the plunger remains motionless until 



STEAM GENERATION AND STEAM BOILERS 35 

the piston C strikes one of the valves I, exhausting the steam 
through the part E at one end. The water end is similar to that 
of the pump in Fig. 29. 

Injectors are used very commonly for the feeding of portable 
and of small stationary boilers. In larger plants injectors are 
sometimes used in conjunction with pumps as an auxiliary 
method for feeding boilers. 

The general construction of an injector is illustrated in Fig. 31. 
Steam from the boiler enters the injector nozzle at A, flows 



Steam 




Fig. 31.— Injector. 



through the combining tube BC and out to the atmosphere 
through the check valve E and overflow F. The steam in ex- 
panding through the nozzle A attains considerable velocity, and 
forms sufficient vacuum to cause the water to rise to the injector. 
The steam jet at a high velocity coming into contact with the 
water is condensed, gives up its heat to the water and imparts a 
momentum which is great enough to force the water into the 
boiler against a steam pressure equal to or greater than that of 
the steam entering the injector. 

As soon as a vacuum is established in the injector, and the water 
begins to be delivered to the boiler, the check valve E at the 
overflow closes. Should the flow of feed water to the boiler be 
interrupted, due to air leaking into the injector or to some other 
cause, the overflow will open and the steam will escape to the 
atmosphere. 

The method of connecting an injector to a vertical boiler is 



36 



FARM MOTORS 



illustrated in Fig. 32. To facilitate the taking down of an injector 
for inspection and repairs it should be connected up with unions. 
Due to the fact that the vacuum in an injector is broken as 
the temperature of the water increases, injectors can only work 
when the feed water is 150°F. or cooler. 




Fig. 32. — Method of connecting an injector. 

Feed-water Heaters. — If cold water is fed to a boiler, the 
temperature at the place where the water is discharged will be 
different from that in the other parts of the boiler, and strains 
due to unequal expansion and contraction will be set up which 
will decrease the life of the boiler, besides impairing the tightness 
of the setting. With hot feed water, strains due to unequal 
expansion are prevented. Also for every 10° increase in the 
temperature of the feed water a gain of about 1 per cent, in the 
fuel economy can be expected. This also means that the capac- 
ity of a boiler plant can be increased by the installation of some 
apparatus, outside of the boiler, for the heating of feed water. 

This increase in capacity can usually be accomplished at much 
less cost than by increasing the size of the boiler. Heating the 
feed water outside of the boiler serves also to purify the water 
before it enters the boiler. 



STEAM GENERATION AND STEAM BOILERS 37 

Feed water can be heated by live steam, by exhaust steam, 
or by the waste chimney gases. 

The heating of feed water by live steam is not recommended, 
as the advantage of this method lies mainly in the amelioration 
of unequal expansion. 

Feed-water heaters which utilize the heat of exhaust steam 
from engines and pumps are most commonly used. Heaters 
may be constructed so that the exhaust steam and water come 
into direct contact and the steam gives up its heat by condensa- 
tion. Such heaters are called open feed-water heaters. In this 
form water passes over trays upon which the impurities thrown 
out of the water by heating it are deposited, and can be easily 
removed. 

If it is desired to prevent the steam and water from coming 
into contact with each other, some form of closed heater should 
be used. In the case of closed heaters the steam on one side of a 
tube heats the water on the other. Such heaters may be con- 
structed so that either the steam or the water flows through the 
tubes. 

Chimneys and Artificial Draft-producing Systems. — A chim- 
ney or stack is used to carry off the obnoxious gases formed dur- 
ing the process of combustion at such an elevation as will render 
them unobjectionable. Another very important function per- 
formed by a chimney is to produce a draft which will cause fresh 
air, carrying oxygen, to pass through the fuel bed, producing 
continuous combustion. 

The draft produced by a chimney is due to the fact that the hot 
gases inside the chimney are lighter than the outside cold air. In 
the boiler plant the cold air is heated in passing through the fuel 
bed, rises through the chimney and is replaced by cold air entering 
under the grate. 

The amount of draft produced by a chimney depends on its 
height ; the taller the chimney, the greater is the draft produced, 
since the difference in weight between the column of the air inside 
and that of the air outside increases as the height of the chimney. 

The intensity of chimney draft is measured in inches of water, 
which means that the draft is strong enough to support a column 
of water of the height given. The draft produced by chimneys is 
usually % to % in. of water. 



38 FARM MOTORS 

Chimneys are made of brick, concrete, or steel. For small 
plants steel stacks are more desirable. A brick chimney unless 
carefully constructed may allow large quantities of air to leak in, 
which will interfere with the intensity of the draft. Steel stacks 
are also cheaper. Brick chimneys as usually constructed have 
two walls, with an air space between them. The inside wall 
should be lined with firebrick. 

Draft produced by chimneys is called natural draft. 

In some cases the draft produced by chimneys is insufficient 
and some artificial method has to be used. 

Artificial draft may be produced by steam jets, as is common in 
locomotive and traction-engine practice. This system is uneco- 
nomical, and is used only in connection with land boilers to 
reduce the clinkering of certain grades of coal. 

Firing. — To the average person firing consists merely of open- 
ing the furnace door and throwing fuel on the grate. It has been 
found that some system of firing must be adopted in order to 
produce economical combustion of coal. 

The method to be adopted depends mainly on the kind of fuel. 

The spreading method consists of distributing a small charge 
of coal in a thin layer over the entire grate. This system will 
give satisfactory results with anthracite coal and with some 
bituminous coals. With this method, if the fuel is fed in large 
quantities and at long intervals, incomplete combustion will 
result. 

The alternate method consists of covering first one side of the 
grate with fresh fuel and then the other. The volatile gases 
that pass off from the fresh fuel on one side of the grate are burned 
with the hot air coming from the bright side of the fire. This 
system is best applied to a boiler with a broad furnace. 

The coking method is best adapted for smoky and for the cak- 
ing varieties of bituminous coal. In this method the coal is put 
in the front part of the furnace, and allowed to remain there until 
the volatile gases are driven off; it is then pushed back and spread 
over the hot part of the furnace, and a new charge is thrown in the 
front. 

Either one of the three systems of firing explained will produce 
good results, if properly carried out and if the fire is kept bright 
and clean. Smoke indicates incomplete combustion and with 



STEAM GENERATION AND STEAM BOILERS 39 

bituminous coal occurs if the volatile gases are allowed to pass off 
unburned. If the boiler is set too close to the grate, the volatile 
gases driven off from the coal are brought into contact with the 
comparatively cool surfaces of the boiler shell or tubes and smoke 
is produced. 

In all cases the best results can be obtained by firing coal 
frequently and in small quantities. With mechanical stokers 
this can be accomplished and one man can attend to a large 
number of furnaces. 

When using mechanical stokers inferior fuels can be burned 
without smoke, but for small power plants they are not practical 
on account of the initial high cost, large repair bills and cost of 
power for operating the stoker mechanism. 

Rating of Boilers. — Boilers are usually rated in horsepower. 
The term horsepower in this connection is only a matter of con- 
venience in rating boilers, and does not mean the rate of doing 
work, but is an arbitrary unit applying to the evaporation of a 
definite amount of water. The American Society of Mechanical 
Engineers has recommended that one boiler horsepower should 
mean the evaporation of 30 lb. of water per hour at 100°F. into 
steam at 70 lb. gage. This is equivalent to the evaporation of 
34% lb. of water from feed water at 212°F. into steam at 212°F. 

Boiler manufacturers often rate boilers in square feet of heating 
surface. It has been found that each square foot of boiler heat- 
ing surface can evaporate economically 3 to 3.4 lb. of water, so 
that a boiler horsepower can be produced by 10 to 12 sq. ft. of 
boiler heating surface. 

Management of Boilers. — Before a boiler is started for the 
first time, its interior should be carefully cleaned, care being taken 
that no oily waste or foreign material is left inside the boiler. 
The various manholes and handholes are then closed and the 
boiler is filled to about two-thirds of its volume with water. The 
fire is started with wood, oily waste, or other rapidly burning 
materials, keeping the damper and ashpit door open. The fuel 
bed is then built up slowly. 

While getting up the steam pressure, the water gage glass 
should be blown out to see that it is not choked, the gage cocks 
should be tried and all auxiliaries such as pumps, injectors, pres- 
sure gages, piping, etc., carefully examined. The safety valve 



40 FARM MOTORS 

should be carefully examined and tried out before cutting the 
boiler into service. 

When cutting a boiler into service with other boilers, its pres- 
sure should be the same as that of the other boilers. Steam 
valves should be opened and closed very slowly in order to pre- 
vent water-hammer and stresses from rapid temperature changes. 

During the operation of a steam boiler the safety valve should 
be kept in perfect condition and tried daily by allowing the pres- 
sure io rise gradually until the valve begins to simmer. Each 
boiler should have its own safety valve and under no condition 
should a stop valve be placed between it and the boiler. The 
steam gage should be calibrated from time to time with a stand- 
ard gage or still better by means of some form of dead-weight 
tester. It is best not to depend on the water gage glass entirely. 
Gage cocks are more reliable and should be used for checking the 
water level of a boiler. 

In case of low water do not turn on the feed, but shut the 
damper, cover the fuel bed with ashes, or if that is not avail- 
able, with green coal. In case of low water the safety valve 
should not be lifted until the boiler has cooled down, or an ex- 
plosion may occur. Operating conditions, as regards the use 
of steam, should not be changed. If the engine is running 
allow it to continue, but do not open valve to reduce the 
pressure. 

A boiler should be cleaned often and kept free from scale. If 
clean water is used a boiler may be run several months without 
fear of serious scale formation, but in most places boilers should be 
cleaned at least once each month. When preparing to clean a 
boiler allow it to cool down, and the water to remain in the shell 
until ready to commence cleaning. 

In emergencies split tubes may be plugged with iron plugs 
without throwing the boiler out of service. Also if a tube 
becomes leaky in the tube-sheet this can be remedied by inserting 
a tapering sleeve slightly larger than the inside diameter of the 
tube. 

A boiler should always be thoroughly inspected before it is 
started up. In the case of the locomotive type of traction 
engine boiler (Fig 159) the crown sheet should be given par- 
ticular attention. 



STEAM GENERATION AND STEAM BOILERS 41 

Problems: Chapter III 

1. Sketch and explain the fundamental parts of a steam power plant. 

2. Sketch and explain the use of the various kinds of pipe fittings. 

3. Explain, using clear sketch, the construction and use of a steam gage. 

4. Sketch and explain the action of some form of feed pump. 

5. Sketch and explain the action of a steam injector. 

6. Give three- reasons for using feed-water heaters. 

7. Explain the fundamentals of good firing. 

8. Calculate the heat contained in 7 lb. of dry steam at 100 lb. absolute. 

9. If the steam in the above problem contained 5 per cent, moisture, 
calculate heat contained in 1 lb. 

10. Calculate 4he volume of 3 lb. of steam at atmospheric pressure, and 
also at a pressure of 150 lb. absolute. 

11. If steam at a pressure of 125 lb. absolute has a temperature of 390°F. r 
is it saturated? 

12. Taking the weight of a gallon of water as 8}i lb. and using the values 
given in Tables 2 and 4, compare the heat units contained in a gallon of gaso- 
line and kerosene. 

13. If a ton of ice melts (at a temperature of 32°F.) in 24 hr., how much 
heat will it abstract during that time from the surrounding substances? 

14. Explain the meaning of boiler horsepower. Is there any relation 
between boiler horsepower and engine horsepower? Explain in detail. 

15. Give directions for handling a boiler plant. 

16. What should be done in case of low water? 

17. What should the fireman do if he finds that the steam-pressure is 
excessive ? 

18. Give directions for firing bituminous coal. 



CHAPTER IV 
STATIONARY STEAM ENGINES 

Description of the Steam Engine. — A steam engine is a motor 
which utilizes the energy of steam. It consists essentially of a 
piston and cylinder with valves to admit and exhaust steam, 
a governor for regulating the speed, some lubricating system for 
reducing friction, and stuffing boxes for preventing steam leakage. 

In its simplest form, the steam hammer, the steam acting on 
the piston lifts weights against the force of gravity. 




Fig. 33. — Engine cylinder and steam chest. 

In the steam engine working as a motor continuous rotary 
motion of a shaft is essential. This is accomplished by the inter- 
position of a mechanism consisting of a connecting rod and crank, 
which changes the to-and-fro or reciprocating motion of the piston 
into mechanical rotation at the shaft. A steam engine in which 
the reciprocating motion of the piston is changed into rotary mo- 
tion at the crank is called a reciprocating steam engine to differen- 
tiate this form of motor from the steam turbine to be described 
later. 

42 



STATIONARY STEAM ENGINES 



43 



The various parts of a steam engine are illustrated in Figs. 33 
and 34. 

Steam from the boiler at high pressure enters the steam chest 
A, Fig. 33, and is admitted through the ports BB alternately to 
either end of the cylinder by the valve C. The same valve 
also releases and exhausts the steam used in pushing the piston 
D. E is the cylinder in which the steam is expanded. The 
motion of the piston D, Fig. 34, is transmitted through the piston 




Fig. 34. — Steam engine. 

rod F to the crosshead G, and through the connecting rod H 
to the c'rank / which is keyed to the shaft K. 

The shaft is connected directly, or by means of intermediate 
connectors such as belts or chains, to the machines to be driven. 

The shaft carries the flywheel L, the function of which is to 
make the rate of rotation as uniform as possible and to carry 
the engine over dead-center. The dead-center occurs when the 
crank and connecting rod are in a straight line at either end 
of the stroke, at which time the steam acting on the piston will 
not turn the crank. A flywheel is sometimes used as a driving 
pulley, as shown in Fig. 35. 

The eccentric shown in Fig. 35 also rotates with the shaft. An 
eccentric is a crank of special form which imparts reciprocating 
motion to the valve through the eccentric rod and valve stem. 



ft 
44 



FARM MOTORS 



The eccentricity of the eccentric is the distance between the 
center of the eccentric and the center of the shaft. The travel of 
the valve is equal to the throw of the eccentric, or twice the eccen- 
tricity. Changing the eccentricity changes the travel of the 
valve. 

Stuffing boxes which prevent the escape of steam around the 
rods are illustrated at M and N in Figs. 33 and 34. 



Top Cylinder-^^z 
Hkad 



Cylinder— 
LacjOjiHoj 



fiB *M( /#Mfer ^Wr 



Cross- Head— 
Oiler Bracket 



Valve Stem Driver 
Valve Stem Scware 



Drivinq 
Pulley 




^Eccentric Strap 
Eccentric 



Crank Shaft-' 
^-Eccentric Strap 



Fig. 35. — Vertical steam engine. 

The size of a steam engine is given in terms of the cylinder 
diameter and length of stroke of the engine. Thus if an engine 
is called an 8-in. by 10-in. engine, this means that the diameter 
of its cylinder is 8 in. and its stroke or piston travel is 10 in. 

Action of the Plain Slide Valve. — The action of the plain slide 
valve will now be taken up in detail, as a thorough knowledge 
of this type of valve will enable one to understand all other 
forms. Referring to Fig. 36, which shows a section of a cylinder 
with the slide valve in mid-position, A and B are the steam ports, 



STATIONARY STEAM ENGINES 



45 



which lead to the two ends of the cylinder; C is the exhaust 
space. The steam ports are separated from the exhaust space 
by the two bridges D and E. F is the steam chest. V is a plain 
slide valve, commonly called a D slide valve. The amount $ 




Fig. 36. — Engine cylinder and plain slide valve. 



that the valve V overlaps the outside edge of the port, when in the 
middle of its stroke, is called the steam lap. Similarly the 
amount by which the valve overlaps the inside edge of the port 




Fig. 37. — Admission. 



Fig. 38.— Cut-off. 



when it is in mid-position is called the exhaust lap. M and N 
are the steam and exhaust pipes respectively. 

The four valve events are : admission, cutoff, release and com- 
pression. Admission is that, point at which the valve is begin- 
ning to uncover the port, as shown in Fig. 37. Cutoff occurs 



46 



FARM MOTORS 



(Fig. 38) when the valve covers the port, preventing further admis- 
sion of steam. This is followed by the expansion of the steam 
until the cylinder is communicated with the exhaust opening, 
at which time release, as shown by Fig. 39, occurs. Compression 
occurs when communication between the cylinder and exhaust 
opening is interrupted (Fig. 40) and the steam remaining in the 
cylinder is slightly compressed by the piston. The valve is in 




Fig. 39. — Release. 



Pig. 40. — Compression. 



the same position at cutoff as it is at admission, only it is travel- 
ing in the opposite direction. Similarly the positions of the valve 
are the same at release and compression. 

By lead is meant the amount that the port is uncovered when 
the engine is on either dead-center. The object of lead is to 
supply full pressure steam to the piston as soon as it passes the 
dead-center. 




Valve without laps. 



If a valve is constructed without laps, as shown in Fig. 41, 
steam would be admitted to the cylinder at one end or the other 
and exhausted at the opposite end, if the valve is moved slightly 
in either direction. This would mean that steam admission 
at one end would take place throughout the entire stroke of the 
piston and would be exhausted from the opposite end at the 
same time. It is evident that a valve without laps will have 



STATIONARY STEAM ENGINES 



47 



no cutoff and steam will not be used expansively. To use steam 
without expansion is very uneconomical and is resorted to only 
in direct-acting steam pumps. For best economy a steam engine 
should be provided with a valve which cuts off at about one-third 
of the stroke. 

Types of Steam-engine Valve Gears. — The simplest type of 
valve for steam engines is the single-slide valve, which controls 



Valve 



■"Balance Plate 
Steam Port / Steam„Chest: Cover 



Packing 
Packing Gland 



Packing 
Packing Gland 




Counter Bore 
Piston 'Ring 



Fig. 42. — Balanced valve. 



the admission and exhaust of steam alternately to each end of the 
cylinder. The form shown in Fig. 33 is called a piston valve. In 
the position shown it admits steam to the head of the cylinder, 
the end farthest away from crank, and at the same time exhausts 
the steam from the crank end of the cylinder. 

Still a simpler type of valve, the plain slide valve, often used 
on portable and on traction engines, is shown in Fig. 36. The 
objection to this type of valve is that it is not balanced, and, 
either the friction of the valve on its seat is excessive, or the valve 
allows steam to leak into the exhaust space. This is remedied 



48 



FARM MOTORS 



by the piston valve shown in Fig. 33, which is perfectly balanced, 
or by some form of balanced slide valves, illustrated in Fig. 42, 
which works between the valve seat and a balance plate with 
an accurate mechanical fit. 

Valve Setting.— The object of setting valves on an engine is to 
equalize as much as possible the work done on both ends of the 
piston. A valve may be set so that both ends have the same 
lead, or so that the point of cutoff is the same at both ends. 

Before a valve can be set, the dead-centers for both ends of 
the engine must be accurately determined. 

The method of setting an engine on dead-center can best be 
understood by referring to Fig. 43. H represents the engine 



M 



J} 




//////////^ 

Fig. 43. — Valve setting. 

crosshead which moves between the guides marked G, N is the 
connecting rod, R the crank, F the engine flywheel, and a 
stationary object. 

To set the engine on dead-center, turn the engine in the direc- 
tion in which it is supposed to run, as shown by the arrow, until 
the crosshead is near the end of its head-end travel, and make 
a small scratch mark on the crosshead and guide, as at A. At 
the same time mark the edge of the flywheel and the stationary 
object opposite each other, as at B. Turn the engine past dead- 
center, in the same direction as shown by the arrow, until the 
mark on the crosshead and that on the guide again coincide at A, 
and mark the flywheel in line with the same point on the station- 
ary object, obtaining the mark C. The distance between the 
two marks on the flywheel is now bisected at E. If the mark E 



STATIONARY STEAM ENGINES 49 

on the flywheel is now placed in line with the mark on the station- 
ary object, the engine will be on the head-end dead-center. 
Similarly the crank-end dead-center can be found. 

The stationary object may be a wooden board, or a tram may 
be used with one end resting on the engine bedplate and with 
the other end used for locating the marks B, C, and E on the 
flywheel. 

If a valve is to be set for equal lead on both ends, set the 
engine on the dead-center by the method given above, remove 
the steam-chest cover, and measure the lead at that end. Move 
the engine forward to the other dead-center and measure the lead 
again. If the lead on the two ends is not the same, correct half 
the error by changing the length of the valve stem, and the other 
half by moving the eccentric. 

To set an engine for equal cutoff, turn the engine until the 
valve cuts off at one end and mark the position of the crosshead 
on the guides. Then turn the engine until cutoff occurs on the 
opposite end and again mark this position of the crosshead on 
the guides. If the cutoff occurs earlier at one end than at the 
other, shorten the valve stem until the cutoff is equalized at 
both ends. 

Steam-engine Indicator Cards. — In general the best method 
of setting valves is by means of a steam-engine indicator, ex- 
plained in Chapter II and illustrated in Fig. 1. This form of 
instrument shows directly the action of the steam inside the 
engine cylinder, recording the actual pressure at each interval of 
the stroke. 

An indicator card taken by means of an indicator is shown in 
Fig. 44. The events of stroke on the card are marked: admission 
A, cutoff C, release R, compression K. Fig. 45 shows indicator 
cards taken from two ends of a cylinder with a valve properly 
set, while Fig. 46 shows indicator cards taken from an engine 
where the valve is poorly set. 

Losses in Steam Engines. — The main losses in a steam engine 
are: 

1. Loss in pressure as the steam is transferred from the 
steam boiler to the engine cylinder due to the throttling action 
in the steam pipe and ports. 

2. Leakage past piston and valve. 



50 



FARM MOTORS 




Fig. 44. — Steam-engine indicator card. 



3. Losses due to the condensation of steam in the cylinder 
during part of the stroke. 

4. Radiation losses which take place when the steam passes 
through the steam pipes from the boiler to the cylinder and also 
while the steam is in the cylinder. 

5. Losses of heat in the 
exhaust steam. 

6. Mechanical losses due 
to the friction of the mov- 
ing parts. 

Of the above losses 
those due to the heat car- 
ried away in the exhaust 
steam are greatest and are 
usually 75 per cent, or 
more of the heat supplied 
in the steam. Part of this 
heat can be used for such 
purposes as the heating of 
feed water before it enters 
the boiler, for heating 
buildings, or in employing 
the exhaust steam in con- 
nection with various man- 
ufacturing processes. 

The other great loss is 
that due to the condensa- 
tion of steam which takes 
place when the entering 
steam comes into contact 
with the cylinder walls 
which are at the temp- 
erature of the exhaust 
steam. This loss can be reduced to a considerable extent by 
having the steam entering the cylinder as dry as possible. 
Another method for reducing this loss, which is used in connec- 
tion with large engines, is to compound the engine. 

By compounding is meant the subdivision of the expansion 
of the steam into two or more cylinders. The steam on leaving 




Fig. 45. 



-Indicator cards, valves prop- 
erly set. 




Fig. 46.- 



-Indicator cards, 
properly set. 



valves im- 



STATIONARY STEAM ENGINES 51 

the boiler enters the high-pressure cylinder, is partly expanded, 
and then enters one or more cylinders where its expansion is 
completed to the exhaust pressure. The range of pressures in 
each cylinder of a compound engine being less than is the case 
of a simple, or one-cylinder engine, the temperature difference 
between the incoming and the outgoing steam is less. This lower 
temperature range decreases the condensation of the steam in 
the cylinder. The gain in economy does not usually compen- 
sate for the increased first cost of compound engines as compared 
with simple engines in small sizes. 

Radiation losses in the steam pipes leading from the boilers 
to the engines can be reduced to a minimum by covering the 
pipes. A good pipe covering will save the latent heat in the 
steam that would otherwise be lost, will keep the steam drier, 
and will pay for itself in a very short amount of time. 

The cylinders of most steam engines are now jacketed with 
some good non-conductor of heat and this loss is very small. 

Mechanical losses in steam engines can be reduced by proper 
lubrication. Oil can be applied to the various parts by separate 
sight-feed lubricators and grease cups. Another method is to 
connect an oil tank conveniently located with the various parts 
by adjustable sight-feed tubes, allowing different rates of feed 
to the various bearings. Still another method is to inclose some 
of the parts and make them self-oiling. 

The losses due to leakage past the piston and valves are usually 
very small in well-designed engines. The various forms of 
balanced slide valves can be kept tight by means of balance plates. 

Steam-engine Governors. — The function of a governor is to 
control the speed of rotation of a motor irrespective of the power 
which it develops. In the steam engine, the governor maintains 
a uniform speed of rotation either by varying the initial pressure 
of the steam supplied, or by changing the point of cutoff and 
hence the portion of the stroke during which steam is admitted. 

Governors which regulate the speed of an engine by varying 
the initial pressure of the steam supplied to the engine are called 
throttling governors. This is the simplest form of governor and 
is used mainly on engines of the plain slide-valve type. In 
Fig. 47 is given a section of a throttling governor, showing details. 
This form of governor is attached to the steam pipe at A and is 



52 



FARM MOTORS 



connected to the engine cylinder at B, so that the steam must 
pass the valve V before entering the engine. The valve V is a 
balanced valve and is attached to a valve stem S, at the upper 
end of which are two balls CC. The valve stem and balls are 
driven from the engine shaft by a belt, which is connected to the 
pulley P, and which in turn runs the bevel gears D and E. As 
the speed of the engine is increased the centrifugal force makes 
the balls fly out, and in doing so they force down the valve stem 
S, thus reducing the area of the opening through the valve, and 




Fig. 47. — Steam-engine governor. 

the steam to the engine is throttled. As soon as the engine be- 
gins to slow down, the balls drop, increasing the steam opening 
through the valve V. The speed at which the steam is throttled 
can be changed within certain limits by regulating the position 
of the balls by means of the nut N. 

Most of the better engines are governed by varying the point 
of cutoff and hence the total volume of steam supplied to the 
cylinder. 

In high-speed automatic engines this is accomplished by some 



STATIONARY STEAM ENGINES 



53 



form of flywheel governor which is usually placed on the engine 
shaft, and which controls the point of cutoff by changing the 
position of the eccentric. 

Engine Details. — The general construction of steam-engine 
cylinders can be seen from the previous illustrations. Steam- 




Fig. 49. — Cross-head. 




Fig. 50. — Connecting rod. 

engine cylinders are made of cast iron. As the cylinder wears 
it has to be rebored so as to maintain true inside surfaces. The 
thickness of the cylinder walls not only should be strong enough 
to withstand safely the maximum steam pressure, but should 
allow for reboring. All steam-engine cylinders should be pro- 



54 



FARM MOTORS 



vided with drip cocks at each end in order to drain the cylinder 
and steam chest when starting. 

A good piston should be steam-tight and at the same time 
should not produce too much friction when sliding inside the 
engine cylinder. The piston is usually constructed somewhat 
smaller than the inside diameter of the engine cylinder, and is 
made tight by the use of split cast-iron packing rings. In Fig. 
48 is illustrated a piston with its packing rings. ' 

The general construction of steam-engine crossheads is illus- 




.iMiim«im @ )i> 



Fig. 51. — Eccentric rod and strap. 




Fig. 52. — Main bearings. 

trated in Fig. 49. All crossheads should be provided with shoes 
which can be adjusted for wear. 

Fig. 50 shows a connecting rod. It is connected at one end 
with the crosshead and at the other with the crankpin. A con- 
necting rod should be so constructed that the wear on its bearings 
can be taken up. This is usually accomplished by wedges and 
setscrews as illustrated. 

Some engines have their cranks located between the two bear- 
ings of an engine, and are called center-crank engines. Engines 
which have the cranks located at the end of the shaft and on 
one side of the two bearings are called side-crank engines. 



STATIONARY STEAM ENGINES 



55 



The eccentric is a special form of crank. It is usually set 
somewhat more than 90° ahead of the crank and gives motion 
to the valve or valves in the steam chest of the engine. The 
eccentric is a cast-iron disc through which the shaft passes and 
which gives motion to the valve. Fig. 51 shows an eccentric 
rod and strap. 

The main bearings of steam engines are illustrated in Fig. 52. 
These bearings are usually made in three or four parts and can 
be adjusted for wear by means of wedges and setscrews fastened 
with locknuts. 

Lubricators. — The subject of lubricating the moving parts of 





Fig. 53. — Grease cups. Fig. 54. — Automatic grease cup. 



an engine was treated to some extent in connection with the 
discussion of mechanical losses in steam engines. 

Bearings may be lubricated by grease cups illustrated by 
Figs. 53 and 54. The first type is used on stationary bearings, 
the grease being forced out by screwing the cap down by hand. 
The type illustrated in Fig. 54 is automatically operated, and is 
used for the lubrication of crankpins. 

If oil is used, a plain oil cup, illustrated in Fig. 55, can be em- 
ployed, or some form of sight-feed lubricator, as shown in Fig. 
56. By means of the sight-feed types the flow of oil can be 
regulated and the drops of oil issuing from the lubricator can 
be seen. 



56 



FARM MOTORS 



For the lubrication of steam-engine cylinders some form of 
sight-feed automatic steam lubricator, as illustrated in Fig. 57, 
should be employed. This form of lubricator is used to introduce 
a heavy oil into the steam entering the cylinder. This oil is a 





Fig. 55. — Plain oil cup. Fig. 56. — Sight-feed lubricator. 





Fig. 57. — Sight-feed automatic lubricator. 

specially refined heavy petroleum oil which will neither decom- 
pose, vaporize, or burn when exposed to the high temperature of 
steam. Steam from the pipe leading to the cylinder B is admitted 
through the pipe F to the condensing chamber E, where it is con- 
densed and falls through the pipe P to the bottom of the chamber 



STATIONARY STEAM ENGINES 



57 



A. The oil which is contained in chamber A rises to the top, 
is forced through the tube S, ascends in drops through the 
water in the gage glass H, and into the steam pipe K leading to 
the steam chest. The amount of oil fed is regulated by the 
needle valve E. T shows the amount of oil in the chamber A. 



- — ^f iif r Mm m — 

l^jp^| Will WlilllHIBI lz 1 !! 1 " 1 """""""!'^'" 




j piipiiniiiiiiiw iiiiy 

Fig. 58. — Hand oil pump. 

In order to fill the chamber A, the valves on the pipes F and 
H are closed, the water is drained out through G, and the cap 
D is removed for receiving the oil. 

Fig. 58 shows a hand oil pump which is sometimes used to 
admit oil into the cylinder of an engine when starting. 

Steam Separators. — The function of a steam separator is to 
remove any water which may be con- 
tained in the steam before it enters the 
engine cylinder. A separator placed in 
the exhaust pipe of an engine will remove 
a large part of the oil, making the exhaust 
steam more suitable for heating, manu- 
facturing purposes, or for use in steam 
boilers after condensation. 

The importance of having the steam 
entering the engine cylinder as dry as 
possible was explained in an earlier part 
of this chapter. A good steam separator, 
if of sufficient size, will insure fairly dry 
steam and should be used in connection 
with all stationary steam engines. 

Fig. 59 shows in section one form of 
steam separator. The wet steam enters 
at A, strikes the deflecting plates, its velocity is decreased and 
the entrained water, which is heavier than the steam, falls to 
the bottom and is removed at C by means of a trap. The 
dry steam passes out at B. 




Fig. 



C 

59. — Steam 
rator. 



sepa- 



58 



FARM MOTORS 



The Steam Locomobile or Buckeymobile. — The locomobile, 
as built in Europe, and the Buckeymobile of the United States, 
is a self-contained power plant, which consists of a compound 




steam engine mounted upon an internally fired boiler. An in- 
sulated sheet-metal smoke box incloses both engine cylinders, a 
superheater, all steam piping and valves, and a reheater which 
imparts heat to the steam as it passes from the high- to the low- 



STATIONARY STEAM ENGINES 59 

pressure cylinder. This arrangement utilizes the heat in the 
flue gases for superheating the steam before it enters the engine 
cylinder, for reheating the steam between the high- and the low- 
pressure cylinder, for reducing heat losses within the engine and 
for cutting down the radiation losses of the entire power 
plant. 

The steam from the engine exhausts through a feed-water 
heater into a condenser, where it is condensed (converted into 
water) by direct contact with cold water or by contact with tubes 
through which cold water circulates. 

Fig. 60 shows a longitudinal section of a Buckeymobile with the 
various parts named. 

This form of power plant has found a large field of application 
in Europe on account of its compactness and good fuel economy. 
The Buckeymobile, in small sizes, will no doubt in time be used 
to a considerable extent in rural communities in connection with 
flour mills, for irrigation pumping plants and for electric light 
plants in small towns. The principle of this type of power plant 
should also find successful application in connection with steam 
traction engines. 

Steam Turbines. — The steam turbine differs from the steam 
engine described, in that it produces rotary motion directly and 
without any reciprocating parts. It consists of a stationary 
part and one or more wheels with vanes which are rotated by 
steam striking the vanes. The elastic force of the steam, instead 
of acting on a piston, is exerted on the steam itself, producing a 
drop in pressure and a steam jet of high velocity. 

The steam turbine is best adapted for the driving of elec- 
trical generators, centrifugal pumps and air compressors, cream 
separators and other machinery requiring a high-speed rotation. 

In large sizes the steam turbine is somewhat more economical 
than the reciprocating steam engine and occupies considerably 
less space. The steam turbine requires no internal lubrication, 
and thus the exhaust steam can be used again in the boiler with- 
out requiring oil filtration. For large power plants the steam 
turbine has several other advantages. 

The action of one form of steam turbine used for the driv- 
ing of cream separators is illustrated in Fig. 61. A, B, C and 
D are stationary nozzles in which the steam is completely ex- 



60 



FARM MOTORS 



panded and strikes the vanes V, giving a direct rotary motion 
to the wheel W and also to the shaft S. 

Installation and Care of Steam Engines. — Foundations for 
stationary steam engines are usually put in by the purchaser, the 
manufacturer furnishing complete drawings for that purpose. 
Drawings of a board template are also included. A template is 




Fig. 61. — Steam turbine. 



a wooden frame which is used in locating the foundation bolts 
and for holding them in position while building the foundation. 

Before starting on the foundation a bed should be prepared 
for receiving it. The depth of bed depends on the soil. If the 
soil is rocky and firm, the foundation can be built without much 
difficulty. When the soil is very soft, piles may have to be 
driven. The ground for receiving the piles should be excavated 
to a depth of about 2 ft. 

The wooden template is then constructed from the drawings, 
holes being bored for the insertion of foundation bolts. 

Foundations may be built of masonry or of concrete. If of con- 
crete the mixture should consist of 1 part of cement, 2 parts of 
sharp sand and 4 parts of crushed stone. The stone should be of 



STATIONARY STEAM ENGINES 



61 



a size as will pass through a 2-in. ring. In starting on a con- 
crete foundation, a wooden frame of the exact shape of the founda- 
tion is built. This template is then placed in position in the 
manner shown by Fig. 62, and the bolts are put in, the heads of 
the bolts being at the bottom in recesses of cast-iron anchor plates 
marked P. Often the foundation bolts are threaded at both 
ends and the anchor plates are held in place by square nuts. A 
piece of pipe should be placed around each bolt, so as to allow 




Fig. 62. — Foundation in the process of construction. 

the bolts to be moved slightly to pass through the holes in the 
engine bedplate, in case an error should occur in the placing of 
the bolts, or in the location of the bolt holes in the engine 
bedplate. 

With the frame, template and foundation bolts in place, the 
concrete can now be poured and tamped down. After the con- 
crete has set, the template is removed and the foundation is made 
perfectly level. It is well to allow a concrete foundation to set 
several weeks before placing the full weight of the engine on it. 

When the foundation is ready, the engine is placed in position 
and leveled by means of wedges. The nuts on the bolts are now 
screwed down and the engine is grouted in place by means of 
neat cement, this serving to fill any crevices and to give the 
engine a perfect bearing on the foundation. 

After erecting the engine and all its auxiliaries, including pipes, 
valves, cocks and lubricators, all the parts should be carefully 
examined and cleaned, and a coating of oil should be applied to 
all rubbing surfaces, cylinder oil being used for the wearing 
parts in the Valve chest and cylinder. 



62 FARM MOTORS 

Before the engine is operated for the first time, it is well to 
loosen the nuts and bolts, adjust bearings, and turn the engine 
over slowly until an opportunity has been given for any in- 
equalities due to tool and file marks to be partially eliminated, 
and also to prevent heating that might occur if there was an 
error in adjustment. 

When the engine is ready to start, the boiler valve should be 
slowly opened to allow the piping to warm up, but leaving the 
drain cock in the steam pipe, above the steam chest, open to 
permit the escape of condensation. While the piping is being 
warmed up all the grease cups and lubricators are filled. Before 
opening the throttle valve, all cylinder and steam-chest drain 
cocks should be opened to expel water, and the flow of oil started 
through the various lubricators. The throttle valve is then 
opened gradually, and both ends of the engine warmed up. 
This can be accomplished in the case of a single-valve engine by 
turning the engine over slowly by hand to admit steam in turn 
to each end of the cylinder. In starting a Corliss engine the 
eccentric is unlocked from the pin on the wristplate and the 
wristplate is rocked by hand sufficiently to allow steam to pass 
through each set of valves. The drain cocks are closed soon 
after the throttle is wide open and the engine is gradually 
brought up to speed, provided steam is blowing through. 

When stopping an engine, close the throttle valve. As soon 
as the engine stops, close the lubricators, wipe clean the various 
parts, examine all bearings and leave the engine in perfect 
condition ready to start. 

The above instructions apply to non-condensing engines. 
If the engine is to be operated condensing, the circulating and 
air pumps should be started while the engine is warming up. 
The other directions apply with slight modifications to all types 
of steam engines. 

In regard to daily operation, cleanliness is of great importance. 
No part of the engine should be allowed to become dirty and all 
parts must be kept free from rust. It is well to draw off all the 
oil from bearings quite frequently and to clean them with 
kerosene before refilling with fresh oil. In starting it is well to 
give the various parts plenty of oil, but the amount should be de- 
creased as the engine warms up. An excess of oil should be avoided. 



STATIONARY STEAM ENGINES 63 

Competent engine operators usually make a practice of going 
over and cleaning every bearing, nut, and bolt, immediately on 
shutting down. This practice not only keeps the engine in first- 
class condition, as regards cleanliness, but enables the operator 
to detect the first indication of any defect that, if overlooked, 
might result seriously. 

If a knock develops in a steam engine, it should be located 
and remedied at once. Knocking is usually due to lost motion 
in bearings, worn journals or crosshead shoes, water in the 
cylinder, loose piston, or to poor valve setting. Locating knocks 
in steam engines is to a great extent a matter of experience and 
no definite rules can be laid down which will meet all cases. 

However, the beginner may, by careful attention to the 
machine, learn to trace out the location of a knock in a com- 
paratively short time. He must, however, bear in mind that 
he cannot rely on his ear for locating it, as the sound produced 
by a knock is, in many cases, tramsmitted along the moving 
parts, and apparently comes from an entirely different point. 

A knock, due to water in the cylinder, is usually sharp and 
crackling in its nature, while that in the case of a crank or a cross- 
head pin is more in the nature of a thud. If the knock should be 
due to looseness of the main bearings, the location may be de- 
tected by carefully watching the flywheel, while if the cross- 
heads are loose in the guides the observer may be able to detect 
a motion cross ways of the crosshead, but it is not likely that he 
can do this with accuracy in the case of a high-speed engine, and 
the crosshead should be tested when the engine is at rest. In 
no case should any adjustment be made in bearings or moving parts 
of an engine unless the machine is at standstill or being turned by 
hand; never when under its own power. 

The heating of a bearing is always due to one of five causes : 

1. Insufficient lubrication due to insufficient quantity of oil, 
wrong kind of oil, or lack of proper means to distribute the oil 
about the bearings. 

2. The presence of dirt in the bearings. 

3. Bearings out of alignment. 

4. Bearings improperly adjusted; they may be either too 
tight or too loose. 

5. Operation in a place where the temperature is excessive. 



64 FARM MOTORS 

In case a bearing should run hot and it is very undesirable to 
shut down, it is oftentimes possible to keep going by a liberal 
application of cold water upon the entire heated surface or sur- 
faces. It is sometimes possible to stop heating by changing 
from machine oil to cylinder oil which has a higher flash point. 

Should a bearing, particularly a large one, be overheated to 
the extent that it is necessary to shut down the engine, do not 
shut down suddenly or allow the bearing to stand any length of 
time without attention. This is particularly important in the 
case of babbitted bearings, as the softer metal of the bearings 
will tend to become brazed to, or fused with, the harder metal 
of the shaft, and it may be necessary to put the engine through 
the shop before it can be used again. 

In case of the necessity of shutting down for a hot bearing, 
first remove the load, then permit the engine to revolve slowly 
under its own steam until the bearing is- sufficiently cool to per- 
mit the bare hand to rest on it. 

The presence of water in the cylinder is always a source of 
danger, and care should be taken that the water of condensation 
is thoroughly drained from the cylinder when the engine is first 
started, at shutting down, and at regular intervals throughout 
the operation. An accumulation of water may readily result 
in the blowing out of a cylinder head with its resultant loss to 
property and possibly of life. There are several appliances now 
on the market which automatically safeguard the cylinder head 
by providing a weak point in the drain system which will relieve 
the excess pressure before the cylinder head gives way. 

Problems: Chapter IV 

1. Sketch and explain the action of the plain slide-valve engine. 

2. Explain in detail how to set the valve of a steam engine. 

3. Discuss the losses in steam engines. 

4. Sketch and explain some form of steam-engine governor. 

5. Sketch and explain construction and use of the common grease cup, the 
sight-feed type of lubricator and steam-engine cylinder sight-feed automatic 
lubricator. 

6. Explain the fundamental details of the steam Buckeymobile. 

7. Explain, with sketches, the action of a steam turbine. 

8. Give directions for starting and stopping steam engines. 

9. Give directions for the care of a steam engine. 

10. Explain how to prevent the heating of bearings. 



CHAPTER V 
GAS AND OIL ENGINES 

The Internal-combustion Engine. — The internal-combustion 
engine, commonly called a gas engine, differs from the steam 
engine, in that the transformation of the heat energy of the fuel 
into work takes place within the engine cylinder. The fuel may 
be gasoline, kerosene, crude petroleum, alcohol, illuminating 
gas, or some form of power gas. 

In order to form an explosive mixture in the cylinder, air must 
be mixed in certain proportions with the fuel, and this can be ac- 
complished only when the fuel is in the gaseous state, or is a mist 
of liquid fuel easily vaporized at ordinary temperatures. Thus 
the essential difference among internal-combustion engines using 
the various fuels is in the construction of the device for preparing 
the fuel before it enters the engine cylinder. If the fuel is a gas, 
only a stop valve is necessary between the source and the gas- 
engine admission valve. The devices for preparing liquid fuels 
depend on the character of the fuel, a heavy fuel requiring heat 
while a volatile fuel is easily vaporized at ordinary temperatures 
by being broken up into a fine mist. If the fuel is in the solid 
form, like coal, it must be converted into a gas by the use of a 
gas producer, to be described later, before it can be used in the 
gas-engine cylinder. 

After the mixture is drawn into the cylinder, it is prepared by 
compressing and intimately mixing the fuel with the air at one 
end of the engine cylinder. This highly compressed combustible 
mixture of air and fuel is burned within the cylinder against the 
face of the piston. The heat liberated by the burning gases 
causes these gases to expand, the pressure within the cylinder is 
increased and the piston is driven out toward the other end of 
the cylinder. The motion of the piston is changed into rotary 
motion at the crankshaft through the interposition of the con- 
necting rod and crank. The crankshaft can be connected directly 
to the machines to be driven or through mechanical connectors, 
such as belts and chains. 

65 



66 FARM MOTORS 

The internal-combustion engine, in small sizes, is much more 
economical than the steam power plant. The average small 
steam power plant converts less than 5 per cent, of the heat 
energy in the fuel into useful work. A small oil engine which 
develops a horsepower on 1 lb. of gasoline per hour converts 
nearly 15 per cent, of the heat energy available in the fuel into 
work. 

The Gas-engine Cycle. — The series of events which are 
essential for carrying out the transformation of heat into work 
is called the cycle of an engine. The gas-engine cycle mostly 
used, the Otto cycle, comprises five events, which are: 

1. The mixture of fuel and air must be drawn into the engine 
cylinder. 

2. The mixture must be compressed. 

3. The mixture must be ignited. 

4. The ignited mixture expands doing work. 

5. The cylinder must be cleaned of burned gases in order to 
receive a fresh mixture. 

The above five events in the order explained are usually called : 
suction, compression, ignition, expansion, and exhaust. 

There is another commercial gas-engine cycle, the Diesel, 
which is used in certain types of oil engines. The Diesel cycle 
also requires five events, and differs from the Otto cycle in that 
air without fuel is compressed in the engine cylinder to such a 
great pressure that the temperature resulting is sufficiently 
high to ignite the fuel automatically, as it is sprayed by an 
auxiliary pump into the engine cylinder. 

The compression pressures carried in engines working on the 
Diesel cycle are about 500 lb. per square inch, while those 
carried in engines working on the Otto cycle and with the same 
fuels are 55 to 90 lb. per square inch. 

Classification of Gas Engines. — Gas engines are divided into 
two classes, according to the number of piston strokes required 
to carry out the five events of the gas-engine cycle. To one class 
belong all engines which require four complete strokes of the 
piston, or two complete revolutions of the crankshaft to carry 
out the five events of the gas-engine cycle. These engines are 
called four-stroke cycle engines. The two-stroke cycle engine 
works on the same gas-engine cycle as the four-stroke cycle 



GAS AND OIL ENGINES 



67 



engine, only the mechanism is modified so as to complete the five 
events in two strokes of the piston. 

The Four-stroke Cycle. — The action of an internal-combustion 
engine working on the four-stroke Otto cycle is illustrated in 
Figs. 63 to 67. 



(rt/et/a/ve 



yvzzzBzzzzzzzzzzzzzzzzzzzzzzz n 



Spark Plug 




Fig. 63.— Suction. 

1. Suction of the mixture of air and gas through the inlet 
valve takes place during the complete outward stroke of the 
piston, the exhaust valve being closed. This is shown in Fig. 
63. This stroke of the piston is called the suction stroke. 




Fig. 64. — Compression. 

2. On the return stroke of the piston, shown in Fig. 64, both 
the inlet and exhaust valves remain closed and the mixture is 
compressed between the piston and the closed end of the cylinder. 
This is called the compression stroke. Just before the compres- 



Jn let Valve- 



Exhaust Valve-' 




Fig. 65. — Ignition. 

sion stroke of the piston is completed, the compressed mixture is 
ignited by a spark (Fig. 65) and rapid combustion, or explosion, 
takes place. 

3. The increased pressure within the cylinder due to the rapid 
combustion of the mixture drives the piston on its second for- 



68 



FARM MOTORS 



ward stroke, which is the power stroke. This is shown in Fig. 66. 
This power stroke, or working stroke, is the only stroke in the 
cycle during which power is generated. Both valves remain 




Spark Fluey 



1C~ 



o 




I 



Fig. 66. — Expansion. 



closed until the end of the power stroke, when the exhaust valve 
opens and provides communication between the cylinder and 
the atmosphere. 




■"■■■■' Vulve?ffi\&?77////////////>. 



4P2ZZZZZZZZSB2ZZ233ZZZBZZBZ& 

Fig. 67.— Exhaust. 



4. The exhaust valve remains open during the fourth stroke 
called the exhaust stroke, Fig. 67, during which the burned 
gases are driven out from the cylinder by the return of the piston. 




Fig. 68.- 



Q 

■Suction Stroke s- 

-Gas-engine indicator card. 



An indicator diagram, taken from a four-stroke cycle engine, 
using gasoline as fuel, is illustrated in Fig. 68. IB is the suction 
stroke, BC the compression stroke, CD shows the ignition event, 
DE is the power stroke and EI is the exhaust stroke. The 



GAS AND OIL ENGINES 69 

direction of motion of the piston during each stroke is illustrated 
in each case by arrows. Lines AF and AG were added to the 
indicator diagram; the first is the atmospheric line, while AG is 
the line of pressures. From Fig. 68 it will be noticed that part 
of the suction stroke occurs at a pressure lower than atmos- 
pheric. The reason for this is that a slight vacuum is created 
in the cylinder by the piston moving away from the cylinder 
head. This vacuum helps to draw or suck the mixture into the 
cylinder. 

The engine working on the four-stroke cycle requires two com- 
plete revolutions of the crankshaft, or four strokes of the piston 
to produce one power stroke or working stroke. The other three 
are not only idle strokes, but power is required to move the 
piston through these strokes, and this has to be furnished by 
storing extra momentum in heavy flywheels. Several attempts 
were made from time to time to produce an internal-combustion 
engine by modifying the Otto or Diesel gas-engine cycles, so that 
the working stroke would occur more frequently. This has 
resulted in the so-called two-stroke cycle engine, to be explained 
in the next section, which completes the cycle in two strokes, 
requiring only one complete revolution of the crank. 

The Two-stroke Cycle Engine. — The two-stroke cycle engine 
carries out the gas-engine cycle in two strokes by precompress- 
ing the mixture of fuel and air in a separate chamber, and by 
having the events of expansion, exhaust and admission occur 
during the same stroke of the piston. The precompression of 
the mixture is accomplished in some engines by having a tightly 
closed crank case, and in other types by closing the crank end of 
the cylinder, and providing a stuffing box for the piston rod. 
Large two-stroke cycle engines are usually made double-acting 
and an additional cylinder is provided for the precompression 
of the mixture. 

The principle of the two-stroke cycle internal-combustion 
engine is illustrated in Fig. 69. On the upward stroke of the 
piston P, a partial vacuum is created in the crank case C, and 
the explosive mixture of fuel and air is drawn in through a valve 
at A. At the same time a mixture previously taken into the 
upper part of the cylinder W is compressed. Near the end of 
this compression stroke, the mixture is fired from a spark pro- 



70 



FARM MOTORS 



duced by the spark plug S. This produces an increase in pres- 
sure which drives the piston on its downward or working stroke. 
The piston descending compresses the mixture in the crank 
case to several pounds above atmospheric, the admission valve 
at A being closed as soon as the pressure in the crank case ex- 



Fig 




Two-stroke cycle engine. 



ceeds atmospheric. When the piston is very near the end of its 
downward stroke, it uncovers the exhaust port at E and allows 
the burned gases to escape into the atmosphere. The piston 
continuing on its downward stroke next uncovers the port at /, 
allowing the slightly compressed mixture in the crank case C to 
rush into the working part of the cylinder W. 

The distinctive feature of the two-stroke cycle engine is the 



GAS AND OIL ENGINES 71 

absence of valves. The transfer port i" from the crank case C 
to the working part of the cylinder W, as well as the exhaust 
port E, are opened and closed by the piston. 

Comparison of Two -stroke Cycle and Four-stroke Cycle 
Engines. — To offset the advantages resulting from fewer valves, 
less weight and greater frequency of working strokes, the two- 
stroke cycle engine is usually less economical in fuel consumption 
and not as reliable as the four-stroke cycle engine. As the inlet 
port I is opened while the exhaust of the gases takes place at E, 
there is always some chance that part of the fresh mixture will 
pass out through the exhaust port. Closing the exhaust port 
too soon will cause a decrease in power and efficiency, on account 
of the mixing of the inert burned gases with the fresh mixture. 
By carefully proportioning the size and location of the ports, and 
by providing the piston with a lip L (Fig. 69) to direct the in- 
coming mixture toward the cylinder head, the above losses may 
be decreased. In any case the scavenging of the cylinder 
cannot be as complete in the two-stroke cycle as in the four- 
stroke cycle engine, where one full stroke of the piston is allowed 
for the removal of the exhaust gases. The four-stroke cycle 
engine also has the advantages of wider use and of longer period 
of development. 

The two-stroke cycle engine can be made to run in either 
direction by a simple modification of the ignition timing mechan- 
ism. This feature, and its light weight, makes the two-stroke 
cycle engine especially adaptable for the propulsion of small 
boats. For stationary purposes, in small and medium sizes, 
and for the propulsion of traction engines, automobiles and 
other vehicles, the four-stroke cycle engine is usually to be 
preferred on account of its reliability and somewhat better fuel 
economy. 

Gas-engine Fuels. — Fuels for internal-combustion engines 
may be classified as solid, liquid and gaseous. The value of a 
fuel for gas-engine use depends on the amount of heat liberated 
when the fuel is burned, on the cost of the fuel, and on the cost 
of preparing the fuel for use in the gas-engine cylinder. 

As was explained in the earlier part of this chapter, the fuel 
entering the gas-engine cylinder must be in the form of a vapor 
or a gas. For this reason where a gaseous fuel can be obtained 



72 FARM MOTORS 

at low cost, the complications of the engine mechanism are 
reduced. In or near the natural gas regions, no other gas-engine 
fuel is a competitor of the natural gas. Also in connection with 
certain industrial processes, certain gaseous fuels are obtained as 
byproducts and are utilized with good results in gas engines. 
Illuminating gas is usually too expensive for a gas-engine fuel. 

Where solid fuels are cheap and petroleum oils are expensive, 
an artificial gas, suitable for gas engine use, can be generated in 
a gas producer. A gas producer consists essentially of a tall 
shell filled with coal, coke, or with some other solid fuel and sup- 
plied with a blast of air and steam. Due to the thickness of the 
fuel bed the combustion of the fuel is incomplete and a com- 
bustible gas is formed. The steam supplied with the blast 
enriches the gas and prevents the formation of clinker by keeping 
down the temperature of the fuel bed. Producer gas is not used 
at the present time as a fuel for farm motors, although experi- 
ments are being carried on with a gas producer as a possible 
power plant for gas traction engines. 

As a portable engine for small powers, the internal-combustion 
engine using some liquid fuel has the greatest field of applica- 
tion. Such engines are especially suitable for intermittent work 
and are ideal for farm use. 

The liquid fuels used in internal-combustion engines are gaso- 
line, kerosene, crude petroleum, fuel oil and alcohol. 

Gasoline and Other Distillates of Crude Petroleum. — Gaso- 
line and kerosene are among the fighter distillates of crude petro- 
leum. The so-called distillates are obtained by boiling or 
refining crude petroleum in large retorts or stills, and condensing 
the vapors which are driven off at various temperatures. 

The vapors which are condensed into gasoline are driven off 
at temperatures of 140° to 160°F. The various grades of kerosene 
are the condensed vapors, driven off at temperatures of 250° to 
400°F. , and the heavy oils are driven off at still higher temperatures. 

Of all petroleum distillates, gasoline is the most important 
fuel for small internal-combustion engines. The yield of gaso- 
line, however, is very small in comparison with the heavier dis- 
tillates. By refining American petroleum, an average of less than 
15 per cent, of gasoline is obtained and usually about 50 per cent, 
of kerosene. This makes gasoline more expensive than other 



GAS AND OIL ENGINES 



73 



petroleum fuels. However, as a fuel for small and portable 
engines it has the advantages of quick starting and greater 
reliability, which more than make up for the greater cost. Proc- 
esses are now being perfected for extracting greater quantities 
of gasoline from crude petroleum, and there is little doubt that 
gasoline will remain for many years to come the most important 
fuel for small internal-combustion engines and for gasoline 
automobiles. 

Gasoline has a flash point of 10° to 20°F. This means that it 
forms an inflammable vapor at that low temperature, provided a 
sufficient supply of air is present. For this reason care must be 
taken in the handling of gasoline. A good storage tank free 
from leaks and placed underground contributes 
greatly to the safety, as well as to the econom- 
ical use of gasoline. When filling a gasoline 
storage tank or in handling gasoline, care 
must be taken not to have any unprotected 
flame nearby. In case gasoline takes fire at 
the engine or at the storage tank, it is best 
to extinguish it by means of wet sawdust. 
Sand or dirt will do in an emergency, but if it 
finds its way into the engine cylinder, it may 
cause considerable damage by cutting the rubbing 
surfaces. 

Kerosene, which can be secured in greater 
quantities than gasoline, and which has a rather 
limited market, is the fuel next to gasoline, 
among the products of crude petroleum, for use 
in oil engines. This fuel is more difficult to 
vaporize at ordinary temperatures and presents 
a more difficult problem when used in oil en- 
gines than does gasoline. 

The flash point of kerosene is 70° to 150°F., depending on the 
grade. As the flash point of oil is a measure of its safety, a kero- 
sene of a lower flash point than 120°F. is dangerous for use as an 
illuminating oil in lamps. The lower the flash point of an oil 
the better it is for gas-engine use, as less heat is required to vapor- 
ize it ready for use in the engine cylinder. 

Very light gasoline has a specific gravity of from 0.65 to 0.74. 




Fig. 70.— Hy- 
drometer. 



74 




FARM MOTORS 






Table 5 


— Relation 


between Specific Gravity, the I 


Baume Hy- 




DROMETER 


Scale, and the Weight 


per Gallon 




Specific 
gravity 


Degrees 
Baume 


Pounds per 
gallon 


Specific 
gravity 


Degrees 
Baume 


Pounds per 
gallon 


1.000 


10 


8.336 


0.775 


51 


6.462 


0.993 


11 


8.277 


0.771 


52 


6.428 


0.986 


12 


8.220 


0.767 


53 


6.394 


0.979 


13 


8.161 


0.763 


54 


6.358 


0.972 


14 


8.104 


0.759 


55 


6.324 


0.966 


15 


8.051 


0.755 


56 


6.290 


0.959 


16 


7.997 


0.751 


57 


6.258 


0.953 


17 


7.944. 


0.747 


58 


6.212 


0.947 


18 


7.891 


0.743 


59 


6.195 


0.940 


19 


7.837 


0.739 


60 


6.163 


0.934 


20 


7.785 


0.736 


61 


6.133 


0.928 


21 


7.736 


0.732 


62 


6.101 


0.922 


22 


7.687 


0.728 


63 


6.070 


0.916 


23 


7.638 


0.724 


64 


6.038 


0.911 


24 


7.590 


0.721 


65 


6.006 


0.905 


25 


7.541 


0.717 


66 


5.975 


0.899 


26 


7.493 


0.713 


67 


5.946 


0.893 


27 


7.444 


0.710 


68 


5.916 


0.887 


28 


7.395 


0.706 


69 


5.886 


0.881 


29 


7.347 


0.703 


70 


5.856 


0.876 


30 


7.298 


0.699 


71 


5.827 


0.870 


31 


7.254 


0.696 


72 


5.797 


0.865 


32 


7.210 


0.692 


73 


5.771 


0.860 


33 


7.166 


0.689 


74 


5.743 


0.854 


34 


7.122 


0.686 


75 


5.715 


0.849 


35 


7.079 


0.682 


76 


5.688 


0.844 


36 


7.038 


0.679 


77 


5.659 


0.840 


37 


6.998 


0.676 


78 


5.632 


0.835 


38 


6.696 


0.672 


79 


5.603 


0.830 


39 


6.918 


0.669 


80 


5.576 


0.825 


40 


6.878 


0.666 


81 


5.548 


0.820 


41 


6.839 


0.662 


82 


5.517 


0.816 


42 


6.804 


0.658 


83 


5.487 


0.811 


43 


6.760 


0.655 


84 


5.457 


0.806 


44 


6.721 


0.651 


85 


5.427 


0.802 


45 


6.683 


0.648 


86 


5.402 


0.797 


46 


6.644 


0.645 


87 


5.374 


0.793 


47 


6.608 


0.642 


88 


5.353 


0.788 


48 


6.571 


0.639 


89 


5.316 


0.784 


49 


6.534 


0.639 


90 


5.304 


0.779 


50 


6.498 









GAS AND OIL ENGINES 75 

The specific gravity of kerosene is 0.78 to 0.86, of crude oil 0.87 
to 0.90, and of fuel oil 0.90 to 0.94. The specific gravity of petro- 
leum fuels is usually given in degrees of the Baume hydrometer. 
Commercial gasoline will test from 50° to 65°Be. This means 
that when a hydrometer is placed in the gasoline (Fig. 70), it 
will sink to a depth as will indicate 50° to 65°, the lighter gasoline 
showing the greater value. The relations existing between the 
specific gravity of various liquid fuels, the degrees on the Baume 
hydrometer, and the weight of a fuel in pounds per gallon are 
given in Table 5. 

A study of Table 5 shows that the weight per gallon of the 
heavier oil is greater than that of the lighter oils. Since the 
calorific value per pound of the various petroleum fuels is very 
nearly the same (see Table 4, Chapter III), and liquid fuels are 
bought by the gallon, it is evident that the total heat in a gallon 
of kerosene or in that of the still heavier oil, is much greater than 
the heat in a gallon of gasoline. Kerosene for farm use has the 
further advantages over gasoline in that it can be obtained every- 
where, is cheaper, can be used for illumination in lamps and is not 
so dangerous. 

Any good gasoline engine can be easily changed into one suit- 
able for kerosene fuel. Such engines are started on gasoline and 
changed over to kerosene as soon as the cylinder walls become 
hot. Several types of engines, to be described later, will start 
on kerosene and will also operate on crude petroleum and on 
fuel oil. The first cost of such engines is greater than that of a 
gasoline engine, and these are used mainly in sizes of 25 hp. 
and larger for the driving of pumps in irrigation plants, and also 
in connection with electric light plants for towns or cities. 

The various types of gas tractors, to be described in another 
chapter, are usually started on gasoline and operate with kerosene 
or with solar oil, which is a heavier distillate than kerosene. 

In general, an engine running on petroleum fuel other than 
gasoline is more difficult to start and requires greater care and 
more frequent cleaning of valves and pistons. For small engines 
gasoline has sufficient advantages to give it the preference to the 
cheaper petroleum fuels. 

Alcohol as a Fuel for Gas-engine Use. — Alcohol as a fuel for 
gas-engine use has many advantages as compared with the 



76 FARM MOTORS 

petroleum distillates. It is less dangerous than gasoline, its 
products of combustion are odorless, and it lends itself to greater 
compression pressures than do the various petroleum fuels. 
Experiments show that an engine designed to stand the com- 
pression pressures before ignition most suitable for alcohol will 
develop about 30 per cent, more power than a gasoline engine of 
the same size, stroke and speed. Alcohol, when used as a fuel in 
the ordinary gasoline engine, and with the common compression 
pressures for gasoline fuel, will show a much poorer economy than 
gasoline, or kerosene. Engines operating with alcohol fuel are 
difficult to start and the operation at variable loads is less certain 
than with gasoline fuel. 

Several years ago, when the internal revenue tax was removed 
from alcohol, so denatured as to destroy its character as a bever- 
age, it was expected that denatured alcohol would become a very 
important fuel for use in gas engines. Its price up to this date, 
however, has been so much higher than that of gasoline, the most 
expensive of petroleum fuels, that its use in gas engines is still out 
of the question. It is probable that, as the cost of the petroleum 
distillates increases, and processes are developed for producing 
denatured alcohol at a low price, the alcohol engine will come into 
prominence as a motor for farm use. 

American denatured alcohol consists of 100 volumes of ethyl 
(grain) alcohol, mixed with 10 volumes of methyl (wood) alcohol 
and with 0.5 volume of benzol. 

The specific gravity of denatured alcohol is about 0.795 and 
its calorific value is about two-thirds that of petroleum fuels. 
Alcohol requires less air for combustion than do petroleum fuels. 
Theoretically, the calorific value of a cubic foot of explosive 
mixtures of alcohol and of gasoline is about the same. Actual 
tests show that the fuel economy per horsepower is about the 
same for both fuels provided the compression pressures before 
ignition are best suited for the particular fuel used. In gasoline 
engines, a compression pressure of about 75 lb. is used, while the 
alcohol engine gives best results, as far as economy and capacity 
are concerned, when the compression pressure before ignition is 
180 lb. per square inch. 

Essential Parts of a Four-stroke Cycle Gas Engine. — The 
essential parts of a gas engine are illustrated in Fig. 71. The fuel 



GAS AND OIL ENGINES 



77 



from the liquid fuel tank T is supplied to the mixing valve or 
carburetor through the fuel-regulating valve G. The air, through 
the air pipe A, enters the same carburetor and is thoroughly 
mixed with the fuel. The mixture of air and vaporized fuel enters 
the engine cylinder C through the inlet valve V as the piston P 
moves on the suction stroke. The mixture is then compressed, 
and ignited by an electric spark produced, at the spark plug Z, by 
current furnished from the battery B. The ignition of the mix- 
ture is followed by the power stroke. The reciprocating motion 
of the piston P is communicated, through the connecting rod R, to 




Fig. 71. — Parts of a four-stroke cycle gas engine. 

the crank N } and is changed into rotary motion at the crankshaft 
S. The crankshaft S, while driving the machinery to which it is 
connected, also turns the valve gear shaft, sometimes called the 
two-to-one shaft, through the gears X and Y. The gear Y turns 
once for every two revolutions of the crank, and near the end of 
the power stroke opens the exhaust valve E through the rod D 
pivoted at 0. In larger engines this valve gear shaft also opens 
and closes the admission valve V and operates the fuel pump 
and ignition system. As the temperatures resulting from the igni- 
tion of the explosive mixture is usually over 2,000°F., some 
method of cooling the walls of the cylinder must be used, in order 
to facilitate lubrication, to prevent the moving parts from being 
twisted out of shape and to avoid the ignition of the explosive 
mixture at the wrong time of the cycle. One method of cooling 



78 FARM MOTORS 

gas engines is to jacket the cylinder J, that is, to construct a 
double- walled cylinder and circulate water between the two walls, 
through the jacket space. The base U supports the various 
parts of the engine; the flywheel W carries the engine through 
the idle strokes. Besides the above details, every gas engine is 
usually provided with lubricators L for the cylinder and bear- 
ings, and with a governor for keeping the speed constant at 
variable loads. 

The majority of farm gas engines are of the single-acting type. 
This means the combustion (burning) of the fuel takes place at 
one end of the piston only. 

The various parts of horizontal and vertical gasoline engines 
are illustrated and named in Figs. 72 and 73. 

Carburetors for Gasoline Engines. — The function of a car- 
buretor is to vaporize the gasoline, mix it with the correct pro- 
portion of air to form an explosive mixture and then deliver the 
mixture to the engine cylinder. 

A mixture of fuel and air in the proper proportions is one of the 
most important factors essential to the economical and reliable 
operation of a gasoline engine. If too little air is present, or if 
the mixture is too rich, the fuel will not burn completely. This 
will result in loss of power, the exhaust from the engine will be 
darkened and odorous, and the unburned fuel may explode in the 
exhaust pipe, when it meets more air. If the mixture has too 
little gasoline, or is too lean, it will be slow-burning. In fact, 
it may still be burning when the inlet valve opens on the suction 
stroke, and the flame, flashing back through the inlet valve into 
the carburetor, may produce what is commonly called " back- 
firing." Faulty timing of valves, or a badly leaking valve, may 
also cause back-firing. 

In some early forms of carburetors the air was passed over the 
surface of the gasoline on its way to the engine and became 
saturated with the fuel. In another type, called the bubbling 
carburetor, the air was made to bubble through the fuel. The 
objection to these types of carburetors is that the air combines 
with only the more volatile portion of the fuel, leaving the heavier 
constituents not vaporized. 

The modern carburetors are of the spray or nozzle type, that 
is, the gasoline is injected into the entering air through a nozzle 



GAS AND OIL ENGINES 



79 



\e£7 




Fig. 72. — Hopper-cooled gasoline engine. 



Gasoline 
Throttle 



Filler Cap 



Piston 
Rings 

■Piston 
Pin 
Cylinder 




Fig. 73. — Vertical gasoline engine. 



80 



FARM MOTORS 



in the form of a finely divided spray. In the best forms of spray 
carburetors the fuel is -delivered to the nozzle at constant pres- 
sure by maintaining the fuel at a constant level in the carburetor, 
either by means of an overflow pipe or by a float. 

To the first type belong the mixer valves, or pump-feed car- 
buretors, in which constant pressure is obtained by a pump and 
an overflow pipe keeping the height of the fuel at . a constant 
level in a small reservoir. This type of carburetor is well suited 
for stationary and for semiportable engines. Pump-feed carbu- 
retors are also used to a limited extent on traction engines. This 
form of carburetor is well adapted for a fuel supply which is 
located in a tank underground and at a considerable distance. 

For automobiles, boats, portable engines and for traction 
engines the float-feed type of carburetor is best-adapted. In this 
type of carburetor the gasoline is admitted to a float chamber, by 

gravity, from a tank placed above the 
carburetor. The gasoline flows out of 
the float chamber by a spray nozzle, the 
level of the fuel in the chamber being 
regulated by a copper or by a cork 
float which operates the gasoline valve. 
Most carburetors of the float-feed type 
are automatic in their action in that the 
quality of the mixture is regulated, by 
auxiliary air inlet valves, to suit the 
speed at which the motor is running. 

One form of mixer valve, or pump- 
feed carburetor, is illustrated in Fig. 
74. A pump operated by the valve 
gear shaft of the engine forces the gas- 
supply pipe A to the reservoir B. 
return pipe which maintains the fuel 
in the reservoir, and slightly below the 
point at which the needle valve V enters the gasoline nozzle 
N. When the piston of the engine starts on the suction stroke, 
a partial vacuum is created in the cylinder; the inlet valve is 
opened and a current of air is forced by the atmospheric pressure 
into the cylinder. This current of air enters through the air 
pipe C, attains a high velocity, and carries with it into the cylinder 




Fig 



—Pump-feed car- 
buretor. 



oline through the 
is the overflow or 
at a constant level 



GAS AND OIL ENGINES 



81 



a portion of the gasoline vapor. This is the reason why the air 
passage of a carburetor is so arranged, that the velocity of the 
air is increased as it passes around the gasoline spray nozzle. 
The greater the velocity of the air at the nozzle the more vapor 



Exhaust Port 
Exhaust Va Ire Guide 



Water JackeE 



mter.Outlet 




Pig. 75. — Pump-feed carburetor and engine cylinder. 

is carried into the engine cylinder. When starting an engine by 
hand with this form of carburetor, a damper or throttle in the 
air pipe is closed, so that the velocity 
of the air is increased sufficiently to 
admit the fuel to the cylinder. The rel- 
ative positions of the air throttle and 
mixer are illustrated in Fig. 75. 

Another form of spray nozzle carburet- 
ors is illustrated in Fig. 76. Air enters 
at the lower opening C, gasoline flows in 
at (5), and the mixture of the air and 
fuel leaves the mixer valve at B. The 
amount of gasoline fed is regulated by 
adjusting the needle valve at P. 
When the engine piston moves on its 
outward stroke, the disc F is raised by 
suction, drawing in a charge of air, through the seat open- 
ing and past the gasoline port, into the mixing chamber 
above F. The lift and movement of the valve F, and 
consequently the quantity of the mixture to the cylinder, 
is regulated by the stem (6). The gasoline is supplied from a 
tank above the carburetor. This form of carbureter is much 
used for two-stroke cycle engines, as it facilitates easy starting, 




Fig. 76. — Gravity car- 
buretor. 



82 



FARM MOTORS 



but is somewhat dangerous on account of the possibility of 

gasoline leakage. 

In small stationary engines the form shown in Fig. 77 is often 

used. This carburetor consists essentially of a needle valve N, 

which regulates the fuel, and a check ball valve B which maintains 

the level of the fuel. 

Automatic or float-feed carburetors are provided with two 

chambers, one a float chamber 
in which a constant level of the 
fuel is maintained by means of a 
float, the other a mixing chamber 
through which the air passes 
and mixes with the fuel. The 
float and mixing valves may be 
placed side by side, or the two 
chambers may be constructed 
concentric; that is, the float is 
placed around the spray nozzle. 

The concentric type keeps the fuel at the predetermined level 

much better than the carburetor with the chambers side by side. 




Fig. 77. — Suction-feed carburetor. 




Fig. 78. — Kingston carburetor. 

The concentric float-feed type of carburetor is illustrated in 
Fig. 78. F represents the float, which operates the float valve 
V and regulates the amount of gasoline entering the float chamber 
W through fuel inlet at G. The air inlet to the carburetor is 



GAS AND OIL ENGINES 



83 



at i. S is the gasoline-adjusting screw which regulates the 
needle valve. The mixing chamber around the top of the spray- 
ing nozzle J is constructed so as to increase the velocity of the 
air at that point. This part is called the throat or Venturi tube 
of the carburetor. The amount of mixture which is allowed to 
pass to the engine cylinder is regulated by the throttle E. As 
the throttle E is opened and the speed of the motor increases, the 
velocity of the air at the Venturi passage becomes great and too 
much fuel is pulled in by the air. To overcome this, carburetors 




Fig. 79. — Stromberg carburetor. 

of this type are arranged with auxiliary valves which are con- 
trolled by the balls M. These auxiliary valves admit more air 
as the speed of the motor increases, diluting the mixture before 
it is allowed to enter the engine cylinder. 

A float-feed carburetor with the two chambers side by side is 
illustrated in Fig. 79. In the float chamber is placed a float F 
which operates the float valve V and regulates the amount of 
fuel entering the float chamber W. The main air inlet is at A. 
When the float chamber becomes filled with gasoline to a certain 
level, the float closes the needle valve V, and the flow of fuel is 
stopped. The fuel from the float chamber enters the mixing 
chamber M, at the right, and is picked up by the air entering at A. 
The mixture passes to the engine cylinder through the throttle E. 



84 



FARM MOTORS 



The auxiliary air valve is operated by a spring and regulates 
the quality of the mixture in proportion to the speed of the 




Fig. 81. — Schebler carburetor. 

engine and in a manner similar to the ball valves in the carburetor 
of Fig. 78. In some forms of carburetors an enlarged main air 
inlet takes the place of the auxiliary valve. In others, the con- 



GAS AND OIL ENGINES 85 

nection to the throttle regulates the fuel needle valve, or the air 
inlet, to suit the speed of the engine and the load on the engine. 
Two other forms of float-feed carburetors are shown in Figs. 
80 and 81. The parts of these carburetors are designated by the 
same letters as the similar parts in Figs. 78 and 79. 

The concentric type of carburetor is usually preferred on ac- 
count of the fact that the pressure on the spray nozzle can be 
kept more nearly constant in this type than in the carbureter 
where the float and mixing chambers are placed side by side. 

Floats for carburetors are made either of cork or of metal. 
The hollow metal float is more expensive and is more liable to 
leak. Cork floats, when covered thoroughly with shellac, will 
not lose their buoyancy, but there is some danger that particles 
may become detached from the cork and clog the passages leading 
to the spray nozzle. 

The carburetor float chamber is usually provided with a pet- 
cock at its lowest point (P in Fig. 79), for drawing off poorer 
grades of gasoline and also water. 

In automobile practice, multiple-jet carburetors are sometimes 
used. The multiple-jet carburetor has two or more spray nozzles 
and this enables the engine to draw the correct proportion of fuel 
ard air at high speeds. 

The action of the carburetor, Fig. 80, is that of a multiple-jet 
type. In starting, this form operates as a surface carburetor, 
but the mixture becomes diluted as the engine speeds up. 

Most float-feed carburetors are provided with some hand- 
operated method for priming the carburetor. This is accom- 
plished by depressing the float, so that an excess of gasoline may 
be allowed to enter the mixing chamber. Another method is by 
throttling the air. 

To overcome carburetor troubles on account of climatic con- 
ditions, or where low-grade gasoline is used, the carburetor should 
be jacketed by hot water. A hot-air connection to the carburetor 
will also overcome this difficulty. In automobiles in which the 
thermo-syphon system of water circulation is employed, exhaust 
gases from the engine are used for jacketing the carburetor, 
instead of hot water. Hot jackets are also advantageous in cold 
weather and prevent the use of rich mixtures and the consequent 
low fuel economy. 



86 



FARM MOTORS 



Carbureting Kerosene and the Heavier Fuels. — The various 
forms of carburetors described cannot be used for kerosene or 
for the heavier petroleum fuels, as these fuels are less volatile 
than gasoline at ordinary temperatures and pressures. The 
heavier the fuel the more heat is required to vaporize it. 

A kerosene carburetor, used on some forms of traction engines, is 



J _*IP 



tezzzzzzzzzzzz 




High Speed 
Adjustment 



Fig. 82. — Kerosene carburetor. 



illustrated in Fig. 82; the parts of this carburetor are designated 
by the same letters as similar parts in Fig. 78. 

An ordinary gasoline engine will operate with kerosene fuel, 
if started on gasoline, but carbon deposits in the cylinder will 
necessitate frequent cleaning of the cylinder walls, piston and 
rings. 

Some engines work very successfully with kerosene and the 
heavier distillates, if the fuel is vaporized by the heat secured from 



GAS AND OIL ENGINES 87 

exhaust gases in a coil located entirely outside the engine cyl- 
inder. It has been found that the injection of water with the 
fuel reduces the carbon deposits in the cylinder and improves the 
operation of the engine. Water injection increases the capacity 
of an oil engine when operating with the heavier petroleum fuels, 
but decreases the economy. The supply of injection water 
should be cut off at light loads and used at heavy loads in 
amounts sufficient to prevent preignition. Preignition is indi- 
cated by a metallic knock within the cylinder. 

Oil engines for burning petroleum fuels heavier than 35°Be. 
have been perfected. These engines are either of the Diesel or 
semi-Diesel types, and ignite the fuel automatically. The prin- 
ciple of construction of engines for heavy fuels will be explained 
in the section on "ignition." 

Cooling of Gas-engine Cylinder Walls. — The necessity for 
cooling gas-engine cylinder walls was explained in an earlier part 
of this chapter. In smaller engines only the cylinder or cylinder 
and cylinder head must be cooled. In large engines it becomes 
necessary to cool also the piston and exhaust valve. 

Three methods are used for cooling gas engines: 

1. Air-cooling. 

2. Water-cooling. 

3. Oil-cooling. 

An air-cooled gasoline engine is illustrated in Figs. 83 and 84. 
The cylinder is cast with webs, and air is circulated by means of 
a fan driven from the engine. In very small engines natural\ir 
circulation is used. The air-cooling system has not been found 
practical for stationary engines above 5 hp. Even for small 
engines there is no positive temperature control with this system 
of cooling. This often results in the decomposition of the cylinder 
oil and in carbon deposits on the piston and cylinder walls. 

Cooling of cylinder walls by means of water is the most com- 
mon method. In this case the cylinder barrel or the cylinder 
barrel and cylinder head are jacketed; that is, they are built with 
double walls and water is circulated through the space between 
the walls. One method of water-cooling was illustrated in con- 
nection with the hopper-cooled engine in Fig. 72. In this case 
the water is heated by contact with the hot cylinder walls, rises 
and is replaced by cooler water. 



88 



FARM MOTORS 



Another system of water-cooling is to place a galvanized- 
iron tank filled with water near the engine and connect the lower 
part of the cylinder jacket to the bottom of the tank and the 
upper part of the jacket at the top of the tank (Fig. 85). The 
cold water enters the jacket at the bottom, is heated, rises and 




Fig. 83. — Air-cooled cylinder. 



flows to the upper part of the tank, the water circulation being 
similar to that of the hopper-cooled engine. 

In order to definitely control the temperature of the water 
jacket, the forced system of water circulation shown in Fig. 71 
is preferable to the two described. This system is used when a 
constant source of water supply is available. The temperature 
in the jacket is usually maintained at about 150°. 



GAS AND OIL ENGINES 



89 




Fig. 84. — Air-cooled engine. 



.Wafer [eve/ 




Fig. 85. — Gas-engine water-cooling system. 



90 



FARM MOTORS 



Another method of water-cooling by forced circulation, used 
quite extensively on small stationary and portable engines, is 
illustrated in Fig. 86. The water from the lower part of the tank 
T is forced by a pump through the jacket. The water enters the 
bottom of the jacket, and leaves from the top of the jacket by the 
pipe P. The water is then allowed to pass over the screen S 
and is cooled by evaporation before reentering the tank. The 
advantage of this system is that the screen acts as a cooling tower 




Fig. 86.— Gas-engine water-cooling system. 

and reduces the weight of water which must be carried with the 
engine. 

Automobiles and traction engines are provided with a cel- 
lular or tubular radiator for cooling the water from the cylinder 
jackets. The heated water passes through the radiator, where 
the rush of air to which it is exposed absorbs a portion of the heat 
and cools the water. A fan is arranged for inducing a cold 
current of air through the radiator. 

Oil is being used for cooling gas-engine cylinders to a limited 
extent where the engines are exposed to low temperatures. The 
systems of oil-cooling are similar to water-cooling. In some 
cases natural circulation is employed, using hoppers or tanks, 
while in other types some form of forced cooling like the one 
illustrated in Fig. 71 is used. However, oil is not a satisfactory 



GAS AND OIL ENGINES 91 

cooling medium on account of its inability to take up heat as 
easily as water. 

In some cases non-freezing mixtures composed of water, alcohol 
and glycerine have been used for cooling the cylinders of gas engines. 
Calcium chloride and common salt solutions have also been used to 
some extent for the cooling of engines. These mixtures will tend 
to prevent freezing and the consequent cracking of the jacket and 
cylinder walls during cold weather when the engine is not running. 

When water is the cooling medium, the engine should be pro- 
vided with a drain cock at the lowest point of the jacket, so 
that the jacket can be thoroughly drained in freezing weather. 

Gas-engine Ignition Systems. — Ignition in all modern gas 
engines is accomplished either by an electric spark, or automat- 
ically by the high compression to which either the air or the mix- 
ture is subjected in the engine cylinder. 

In some older makes of engines the hot-tube system of ignition 
is still employed, in which a tube, made of porcelain or of some 
nickel alloy, is open at one end to the cylinder and is closed at 
the other. The closed end of the tube is heated by a Bunsen 
burner. A portion of the explosive mixture is forced into the tube 
during the compression stroke of the piston, and is fired by the 
heat of the tube walls. Accurate timing of the point of ignition 
is quite impossible with the hot-tube system. The only points 
in favor of this system are the low first cost and cost of main- 
tenance as compared with the electric system. 

Electric Ignition Systems for Gas Engines. — Electric ignition 
for farm gas and oil engines has practically superseded every 
other form. 

Electric ignition is produced by an electric spark or arc. 

In one system the spark is similar to that produced when an 
electric circuit is broken by the opening of a switch, or when a 
wire connected to one pole of a battery is drawn across the other 
pole. This method is called the make-and-break system of 
ignition and is produced by contact and then quickly separating 
metallic points which are located within the clearance space of an 
engine cylinder. 

In another system of electric ignition a current of high voltage 
(electrical pressure) is used which jumps across a small air gap. 
This system is called the jump-spark ignition system. 



92 



FARM MOTORS 




5 



The electric current for producing the spark in the make-and- 
break system is usually obtained, from a primary battery of dry 
cells or of wet cells, from a storage battery, from a small low- 
voltage dynamo, or from a low-tension magneto. The electric 
pressure required is about 6 volts and can be produced by a 
battery of four to eight dry cells in series or by a storage battery 
of three or four cells in series. 

The source of current for the jump-spark system may be, a 
battery of dry or of wet cells, a storage battery or a small dynamo. 

Some form of magneto, as will be ex- 
I plained later, is often employed for 

j this system of ignition. 

Those not familiar with the funda- 
mentals of electricity should study 
Chapter X before taking up electric 
ignition. 

The Make -and -break System of 
Ignition. — The principle of the make- 
and-break system is illustrated in Fig. 
87. B is a battery which supplies the 
electric current for ignition. C is an 
inductive spark coil, often called a 
kick coil. It consists of a bundle of small soft iron wires, called 
the core, surrounded by a coil of many turns of insulated copper 
wire through which the current passes. On account of the in- 
ductive action of such a coil, the spark is greatly intensified, 
producing a strong arc with a small current from a battery of 
low voltage. S is a stationary electrode well-insulated from the 
engine and M is a movable electrode not insulated from the 
engine. Both electrodes are set in the combustion space of the 
cylinder. The contact points of the two electrodes are brought 
together by means of a cam T operated from the valve gear 
shaft of the engine. When the switch W is closed, current will 
flow through the circuit as soon as the contact points of the 
electrodes are brought together by the cam T. A sudden break- 
ing of the contact, aided by a spring, causes a spark to pass between 
the points, which ignites the mixture. The more rapidly the 
electrodes are separated the better is the spark produced. 

The contact between the two electrodes of the make-and-break 



Fig. 



87. — Make-and-break 
ignition system. 



GAS AND OIL ENGINES 



93 



system can be made by sliding one contact point over the other, 
this being known as the wipe-spark igniter and is illustrated in 
Fig. 88. A is the movable and B is the stationary electrode. 





i 


(4? 




if 




-% 




s^ 


HIMMyhfc. 




4& 


iws 


11 • 


HFW 






- mm 




!l(k ^- - 




!• 




'*'-'N 






ii * 













Fig. 88. — Wipe-spark igniter. 

Another type, shown in Fig. 89, is called the hammer-break 
igniter. S is the stationary and M is the movable electrode. 





Fig. 89. — Hammer-break igniter. 

The interrupter lever I is operated from a cam on the valve gear 
shaft until the two contact points M and S, which are located in 
the combustion space of the cylinder, are brought into contact. 
At the desired time, I is tripped and flies back, instantly break- 



94 FARM MOTORS 

ing the contact and producing an arc between M and S. Another 
form of hammer make-and-break igniter is illustrated in Fig. 90, 
the contact points of which are designated M and S. 

Wipe-spark igniters (Fig. 88) keep the contact points cleaner 
than hammer-break types (Figs. 89 and 90). The hammer- 
break igniter is more commonly used on account of the easier 
adjustment and less wear of the contact points. 

To determine the point of ignition with the make-and-break 
system, the engine flywheel is turned over slowly until the igniter 
snaps. This is the point of ignition and should be marked on 
the flywheel and frame or on the piston and cylinder, sO that 
the correct timing may be checked at any time. 



Fig. 90. — Hammer-break igniter. 

To secure best results, the points of the igniter must be clean 
and free from carbon and corrosion, all connections must be 
tight, and the wires used for connecting electrodes with source 
of electricity must be of sufficient size to allow the current to 
flow freely. 

The size of the inductance coil to be used in the make-and-break 
system depends upon the speed of the engine. For a high-speed 
engine, a short inductance coil should be employed, as the 
shorter the coil the quicker is the magnet brought to a saturated 
state. In the case of slow-speed engines, a larger coil can be 
used. 

The Jump -spark System of Ignition. — The principle of the 
jump-spark system is illustrated in Fig. 91. A is a spark plug, 
the spark points E and F of which project into the cylinder. 
These spark points are stationary, insulated from each other, 
and separated by an air gap of about ^2 m - When the switch 
W is closed, the current from the battery B flows through the 



GAS AND OIL ENGINES 



95 



timer T, which completes the circuit at the proper time through 
the induction coil I, and the induced high- voltage current pro- 
duces a spark at the spark-plug gap, igniting the explosive mix- 
ture in the cylinder. 

The induction coil I, Fig. 91, differs from the inductance coil 
used in connection with the make-and-break system of ignition, 
in that two layers of insulated wire are wound on the core C of 
the induction coil and only one layer in the case of an inductance 
coil. In an induction coil, one of the layers, called the primary 
P, consists of several turns of fairly large insulated copper wire. 
The other winding, the secondary 
S, consists of many turns of very 
fine insulated wire. The second- 
ary is wound over the primary 
winding, but has no metallic 
contact with the primary. The 
current from the battery B enters 
the primary winding P of the in- 
duction coil and induces a high- 
voltage current in the secondary 
winding S. 

R is the vibrator, sometimes 
called a trembler or an interrupter. 
The function of the vibrator R is 
to interrupt the primary circuit 
with great rapidity; this action induces an alternating current 
in the secondary and a series of sparks at the air gap of the 
spark plug. In some types of induction coils, the vibrator is 
omitted and but one spark is produced at the spark plug. 

K is known as an electric condenser. The condenser consists 
of alternate layers of tin foil and insulating material like paraffined 
paper. The condenser acts like an air chamber of a pump, in 
that it absorbs the excess of current at the primary winding, 
prevents sparking at the vibrator, and gives out this excess at 
the proper time to increase the intensity of the spark. 

The condenser as well as the windings and the core of an in- 
duction coil are placed in a box made of wood, and the space 
between the parts is filled with an insulating material, usually 
paraffin or some similar wax mixture, in order to protect the 




Fig. 91.- 



- Jump-spark ignition 
system. 



96 



FARM MOTORS 



parts from moisture. A complete induction coil for a jump- 
spark system is shown in Fig. 92. Induction coils operate on 
about 6 volts. 

Fig. 93 shows inductance coils suitable for make-and-break 
systems of ignition. 




Fig. 92. — Induction coil. 



Fig. 93. — Inductance coils. 



In automobile practice, where four or more cylinders are used, 
induction coils are made up in units, each unit supplying a spark 
to one cylinder. In some cases each coil has its own vibrator; 
in other types one vibrator, called a master vibrator, 
is so connected that it breaks the current for each 
induction coil in turn. The system with a master 
vibrator produces better timing of ignition, but an 
accident to the master vibrator interrupts the entire 
system. 

A spark plug used in connection with the jump- 
spark system of ignition is illustrated in Fig. 94. 
It consists essentially of two metallic points, 
well-insulated from each other. The central point 
is connected to the binding post which receives 
current from the secondary, or high-tension wind- 
ing of the induction coil. The other point is not 
insulated from the thread, and completes the circuit 
when the spark plug is in the engine cylinder. 

Comparing the two systems of electric ignition, the jump-spark 
system is much more simple mechanically as it has no moving 
parts inside the cylinder. The make-and-break system is simpler 
electrically, requires less care in wiring, does not have to be in- 
sulated so carefully and the spark is more certain. It is difficult 
to lubricate the many mechanical parts of the make-and-break 
system. The make-and-break system is usually used on station- 
ary slow-speed engines and to some extent on traction engines. 




Fig. 94.— 
Spark plug. 



GAS AND OIL ENGINES 97 

The jump-spark system is better adapted for high-speed and 
multiple-cylinder engines than is the make-and-break, and is 
used on automobiles, small stationary engines, marine engines 
and also on traction engines. 

Ignition Dynamos. — An ignition dynamo is a miniature direct- 
current electric generator, built on the same plan as any large dy- 
namo used for lighting (see Chapter X) . It has electromagnets as 
field magnets and is usually of the iron-clad type. One form of 
ignition dynamo is shown in Fig. 95. In using an ignition 
dynamo the internal-combustion engine must be started on 
batteries, as the speed developed when turning the engine by 
hand is insufficient to produce a spark of sufficient intensity by 
the dynamo. As soon as the engine speeds up, the battery 
current is thrown off and the spark is supplied by the ignition 
dynamo. Most ignition dynamos will supply a spark of sufficient 
intensity for a make-and-break system of ignition without an 
inductance coil. A 5-volt and 3- to 5-amp. generator is suitable 
for make-and-break ignition. For jump-spark ignition a special 
induction coil must be used with the ignition dynamo. 

Magnetos. — The magneto differs from the ignition dynamo 
in that its magnetic fields are permanent magnets. For this 
reason it is unnecessary to run the magneto for any length of time 
in order to build up its field. Magnetos can be operated in 
either direction and at any speed. Magnetos may be classed 
under two heads : 

1. High-tension magnetos which generate sufficient voltage to 
jump the gap of a spark plug. 

2. Low-tension magnetos which include all other types and 
are used in place of batteries or of batteries and inductance 
coil. 

Low-tension Magnetos. — The low-tension magneto, shown in 
Fig. 96, is of the direct-current type and differs from the ignition 
dynamo (Fig. 95) in that the magneto field is a permanent mag- 
net. This type of low-tension magneto can be used for charging 
a storage battery or for producing illumination on a very small 
scale. The direct current from the magneto (Fig. 96) is taken 
off by two brushes which press on the opposite sides of a com- 
mutator. This type of magneto is usually driven by a friction 
wheel or by a belt, and must be operated at high speeds. 

7 



98 



FARM MOTORS 



Fig. 97 illustrates a low-tension alternating-current magneto. 
This type of magneto generates an alternating current of high 
frequency and can be used in connection with a vibrating in- 




Ignition dynamo. 



duction coil for jump-spark ignition systems. It is not neces- 
sary that this type of magneto be timed with the engine. 





Fig. 96. — Low-tension direct- 
current magneto. 



Fig. 



97. — Low-tension alternat- 
ing-current magneto. 



The low-tension magneto (Fig. 98) also generates an alternat- 
ing current, but differs from the low-tension magneto of Fig. 97 
in that the alternating current is of low frequency. This type of 



GAS AND OIL ENGINES 



99 



magneto is used mainly for the make-and-break system of igni- 
tion and takes the place of batteries and induction coil. The 
magneto of the type shown in Fig. 98 must be timed with the 





Fig. 98. — Low-tension Fig. 99. — Magneto with circuit-breaker 
low-frequency magneto. and distributor. 




Fig. 100. — Oscillating magneto. 

engine, as the current is produced only for a small portion of a 
revolution. 

The magneto illustrated in Fig. 99 is also a low-tension alter- 
nating-current low-frequency magneto, but is equipped with a 



100 



FARM MOTORS 



circuit-breaker and distributor so that this form can be used for 
jump-spark system when connected with a non-vibrating induc- 
tion coil. This type of low-tension magneto is often used in 
connection with the "dual system;" that is, with Latteries for 
starting and magneto for operating. 

Low-tension magnetos are sometimes built in the form .of an 
oscillating magneto (Fig. 100). The oscillating magneto pro- 




ra-r 1 O O c3 o o 

a a u t* ess 

O-^ ej 53 O OS 0) 

OSOOOPQM 

rH <N 0O rfl id CD I> 



duces a spark irrespective of the speed of the engine, which is an 
advantage in starting. This form of magneto is usually of the 
alternating-current low-frequency type and is best-adapted for 
slow-speed single-cylinder engines. 

High-tension Magnetos. — A high-tension magneto is shown in 
Fig. 101. This type of magneto is used for the jump-spark 



GAS AND OIL ENGINES 



101 



ignition systems and differs from the low-tension magnetos, in 
that the high-tension magneto can generate a high-voltage cur- 
rent without the aid of an induction coil. The armature of the 
high-tension magneto is provided with two windings, a primary 
and a secondary, carries a condenser and has a circuit-breaker 
at one end. 

The high-tension magneto is provided with a distributor if it 
serves an engine with several cylinders. In traction engines 
and other large engines, the high-tension magneto is usually 
equipped with " impulse starters,'' which give intermittent 




Fig. 102.— Timer. 



rotation to the armature or to the rotating element of the magneto 
until the engine has attained a definite speed, after which time 
the magneto operates at constant speed. 

Timers. — The function of a timer is to control the flow of the 
low-voltage current as it comes from the battery or magneto, by 
closing the primary circuit of the jump-spark system at the proper 
time. The timer consists of one stationary and of one rotating part. 
Both parts are insulated electrically from each other. One part 
is constructed of some insulating material, such as rubber or 
wood fiber, and has pieces of metal, called segments, set at defi- 



102 



FARM MOTORS 



nite distances apart, according to the number of cylinders and 
number of induction coils used. As the rotating part revolves, 
it comes into contact with these metal segments, completing the 

circuit. If a four-cylinder engine 
has induction coils for each one 
of the cylinders there is a metallic 
contact piece on the stationary 
part for each cylinder. 

Two forms of timers are illu- 
strated in Figs. 102 and 103. S 
is the stationary part of the 
timer, R is the revolving part, 
and E reprsents the segments 
which make contact as the timer 
revolves. 





Fig. 103.— Timer. 



Fig. 104. — Circuit breaker. 



In automobiles, the timer is connected to the spark lever on 
the steering wheel (Chapter VI) . 




Mag/neto 

Fig. 105. — Wiring diagram, battery and magneto ignition. 

Fig. 104 shows the construction of a circuit-breaker or inter- 
rupter. This form of timer is used in connection with high- 
tension magnetos or with a low-tension magneto and induction 
coil. 



GAS AND OIL ENGINES 



103 



Fig. 105 shows a wiring diagram for a single-cylinder engine, 
with battery and magneto ignition. 

Automatic Ignition for Oil Engines. — One type of oil engine, 
the Hornsby Akroyd, is illustrated in Fig. 106. The engine is 
provided with an unjacketed vaporizer A, which communicates 
with the cylinder by means of the small opening B. This vapor- 
izer is raised to a red heat before starting, by means of a torch, 
and is kept hot by repeated explosions when the engine is running. 
This engine works on the regular four-stroke Otto gas-engine 
cycle. During the suction stroke of the piston only air is sucked 




Fig. 106. — Hot-bulb oil engine. 



into the cylinder and the charge of oil fuel is injected into the 
vaporizer by a pump. On the return stroke the air is compressed, 
forced in the vaporizer, mixed with the fuel and automatically 
ignited. This is followed by the expansion and exhaust strokes, 
as in other internal-combustion engines. 

A modification of this type of engine is the so-called semi- 
Diesel type of oil engine, which is well-adapted for the burning 
of the lowest grades of petroleum fuels. In this case the air is 
compressed to about 250 lb. per square inch before the fuel is 
injected into the cylinder. 

The Diesel engine was mentioned in the first part of this chap- 



104 



FARM MOTORS 



ter. It is very economical for the burning of low grades of fuel, 
but the high first cost of the engine limits its field of application 
in small sizes. 

Lubrication of Gas and Oil Engines. — The selection of the 
proper lubricating oils and of the best oiling devices is of great 
importance, if reliability of operation and long life of an internal- 
combustion engine are desired. 

The extremely high temperatures which are developed within 
the cylinder of a gas engine or of an oil engine and the absence of 
moisture make the selection of the proper oil a necessity. Oils 
employed for lubricating steam-engine cylinders are not suitable 





Fig. 107. — Sight-feed gas-engine oiler. 

for internal-combustion engines. Such petroleum lubricating 
oils should be employed as are light, are fairly thin, will with- 
stand high temperatures, are free from acid and from animal or 
vegetable matter and which will leave no carbon deposits. The 
lubricating oil should flow freely at all seasons of the year and 
should not easily vaporize at the high temperatures. 

Oil which will gum or form carbon deposits will tend to make 
the piston rings stick or may produce preignition. 

Graphite is satisfactory for lubricating certain parts of an 
internal-combustion engine outside the cylinder. In general, 
the gas-engine oil used for lubricating the engine cylinder will be 



GAS AND OIL ENGINES 



105 



found satisfactory for bearings and other parts, but in large 
engines a saving can be produced by employing a cheaper oil 
for the bearings. 

Single-cylinder gas and oil engines are usually lubricated by a 
sight-feed oiler (Fig. 107). 
This oiler differs from the 
ordinary sight-feed oiler in 
that a check ball ( U) is used 
in order to guard the oiler 
during a portion of the cycle 
from the pressure within the 
cylinder. 

The mechanical oiler (Fig. 
108)holdsa large quantity of 
oil, is positive in action and 

requires little care. In high-speed motors, the forced-flooded 
system of lubrication is commonly employed (Fig. 109). In this 





Fig. 109. — Forced-flooded lubrication system. 

system a pump forces oil to the various bearings, keeping them 
flooded with oil at all times. 

The splash system of oiling is usually more satisfactory with 



106 FARM MOTORS 

gasoline engines than with kerosene engines, as the kerosene 
which gets by the piston is injurious to the lubricating properties 
of the oil in the crank case. 

Governing of Gas Engines. — Every gas engine must be pro- 
vided with some governing mechanism in order that its speed 
may be kept constant as the power developed by the engine 
varies. The governing mechanism is operated by the speed 
variations of the engine and the speed control is accomplished 
by the following methods. 

1. Hit-or-miss Governing. — In this system the number of 
explosions is varied according to the load on the engine. This 
can be carried out in several ways, depending on the valve gear 
of the engine. 

In the case of small engines, where the inlet valve is auto- 
matically operated by the vacuum created in the cylinder during 
the suction stroke, the governor operates on the exhaust valve 
by holding it open during the suction stroke. The free communi- 
cation of the engine cylinder with the outside prevents the forma- 
tion of sufficient vacuum in the cylinder to lift the inlet valve. 

When the inlet valve is mechanically operated from the valve 
gear shaft, the governor acts on the inlet valve, keeping it closed 
part of the time at light loads. The governor used to accomplish 
this is usually some form of flyball governor. As the speed of 
the engine increases, the balls are thrown out by centrifugal 
force and shift the position of a cam on the valve gear shaft, pre- 
venting the opening of the inlet valve. 

The hit-or-miss system of governing can also be carried out by 
having the governor open a switch, thus interrupting the flow 
of current to the igniter, as the load decreases. This method is 
very wasteful of fuel as the fuel drawn in at each suction stroke 
passes through the engine and is wasted. It should be used 
only in connection with one of the other methods of governing. 

The hit-or-miss system of governing is very simple and gives 
good fuel economy at variable loads. As the explosions in the 
engine do not occur at regular intervals, this system of governing 
necessitates the use of very heavy flywheels in order to keep the 
speed fluctuations within practical limits. The hit-or-miss 
system is very well-adapted for small and also for medium-sized 
engines where very close speed regulation is not essential. 



GAS AND OIL ENGINES 



107 



2. Varying Quantity of Mixture. — In this system the propor- 
tion of air to fuel is kept constant and the quantity of the mix- 
ture admitted into the cylinder is varied according to the load. 
This variation is accomplished either by throttling the charge or 
by changing the time during which the inlet valve is open to the 
cylinder. In fact, the two methods of varying the quantity of 




Silo filling. 



the mixture are similar to those used in governing steam engines 
and as explained in Chapter IV. 

3. Varying Quality of Mixture. — In this case the total quantity 
admitted into the cylinder is kept constant, but the amount of 
fuel mixed with the air is varied according to the load. 

When gas engines are governed by varying the quantity or 
quality of the mixture, the speed is more uniform at variable 
loads. Also, since the explosions occur at definite periods, the 



108 



FARM MOTORS 



temperatures inside the cylinder are kept more constant. The 
throttling form of governor is used most commonly with trac- 
tion engines. 




Fig. 111. — Gasoline-engine and sheller mounting. 




Fig. 112. — Engine driving a hay press. 

The Gasoline Engine on the Farm. — Some of the uses to which 
a gasoline engine can be applied on the farm are illustrated in 
Figs. 110 to 117. 



GAS AND OIL ENGINES 



109 



A 12-hp. gasoline engine is used for silo filling in Fig. 110. 
Fig. Ill illustrates a gasoline engine applied to shelling corn. 





■.% ,-*."-"- V .„„ % 








jBt\.— ^ \ 








n^A, ^*%«Mtei^l_ 


JyL~*jp 






ttflEW . I 


Jw&% ti 




'- * >*?%« 









Fig. 113. — Engine driving binder. 




Fig. 114. — Spraying outfit. 



A 7-hp. engine driving a hay press is illustrated in Fig. 112. 

A binder driven by a 4-hp. engine is shown in Fig. 113. 

An air-cooled gasoline engine of 2 hp., direct-connected to a 



110 



FARM MOTORS 





1 

1 

1 

i 






1 

■!>" 

i ^ 

r- 

r. 


p| r 



Fig. 115. — Pumping water. 







■ S> ■■ ". ; ■¥:': ''■' 


■ 


■-•' ': ^ ■■-^ U - : 


. .. . ;v' \ 'j . ; 










l -~~%SfflBu^ 


V^!| 


B> 








^ i 



Fig. 116. — Driving cream separator. 



GAS AND OIL ENGINES 111 

spraying outfit (Fig. 114), is capable of producing a pressure of 
100 lb. per square inch or more, as compared with about 50 lb. 
in the case of the hand sprayer. 

The application of the gasoline engine to pumping water for 
farm use is illustrated in Fig. 115. 

Fig. 116 shows the application of the small gasoline engine for 
the driving of cream separators. 

A wood-sawing rig, Fig. 117, can be removed by loosening 
clamp bolts, and the engine used for grinding feed, pumping, 
shredding, or for any other farm work within its capacity. 




Fig. 117. — Wood-sawing rig. 

Other uses to which the gasoline engine can be put include: 
the driving of cement mixers and rock crushers, the grinding of 
feed, the driving of grindstones and other tools in the farm shop, 
the driving of electric generators for farm fighting (see Chapter 
X), and for various other work about the house, barn and dairy 
which require power. 

Gas tractors and their field of application will be taken up in 
Chapter VII. 

Selection and Management of Gas and Oil Engines 

Selecting a Gas Engine. — A gas engine should be selected 
large enough to do the required work, as it will stand but little 
overload. This is due to the fact that the gas engine develops 
its maximum power when a full charge of the best mixture of 



112 FARM MOTORS 

fuel and air, at the maximum density, has been admitted to the 
engine cylinder. On the other hand, an engine too large for 
the work it has to do will give poor fuel economy. 

As the economy is very nearly independent of the size of the 
gas engine, it is better to buy two small engines than one large 
one. This applies especially to the farm, where the larger engine 
of 6 to 10 hp. can be used for the heavier work, such as feed 
grinding, threshing, wood sawing, etc., and a small engine of 
about 2 hp. for the many small tasks, about the house, dairy, 
and barn, which require but little power. An engine of 2 hp. 
is sufficient to drive a small dynamo, to light the house, barn, etc., 
and to charge a storage battery (see Chapter X). The same 
engine, if portable, can be used for driving a washing machine and 
wringer, a tree-sprayer outfit, a house pump, a cream separator, 
etc. 

An engine governed by the hit-or-miss principle should carry 
such a load as will enable it to miss one explosion in every eight, 
as this will keep the cylinder free from inert burned gases and will 
improve the economy. If an engine is worked at its maximum 
power the largest part of the time, the wear on the parts will be 
too great. 

An engine for farm use must be capable of being started 
easily and should be simple in construction. Every gas engine 
must have certain parts to carry out the cycle of operations, as 
explained in the earlier part of this chapter, but some engines 
are provided with many attachments, which have good points, 
but which complicate the engine so that the first cost is greater 
and the manipulation more difficult. An engine to be of value on 
the farm must be sufficiently simple in construction that ordi- 
nary adjustments and repairs can be made without the aid of 
experts. 

In regard to the method of igniting the mixture, the electric 
system is best for gasoline engines. It is well to provide a gaso- 
line engine with a magneto or ignition dynamo, as with batteries 
the cost of upkeep is considerable and the reliability of opera- 
tion uncertain. Regarding drives for magnetos, friction and 
belt drives should not be selected, as they are not reliable. A 
magneto should always be positively driven from the engine by 
gears. 



GAS AND OIL ENGINES 113 

There is very little choice between the jump-spark and the 
make-and-break systems of ignition. For stationary engines 
the make-and-break is commonly used while the jump-spark is 
more common on automobiles and traction engines. No matter 
which system of electric ignition is selected, the various wires 
should be well-insulated, and inclosed in some moisture-proof 
conduit. 

For irrigation work where the cost of fuel is an important item, 
an engine should be selected which will operate with the cheaper 
fuels. For engines under 100 hp., those which will burn kerosene 
or solar oil will usually be found satisfactory. Such engines 
employ electric ignition and the fuel is vaporized in a coil entirely 
outside the engine cylinder. For work requiring 100 hp. and 
more the various engines with automatic ignition, which use fuel 
oil, will be found more economical. 

It is essential to select an engine from a reputable manufacturer. 
Every engine is subject to breakage of parts and it is important 
that duplicate parts may be easily secured. It is also well to 
investigate the work done by engines of various makes before 
making the final selection. 

The rated horsepower of an engine does not often mean the 
same actual power for different makes of engines. An engine 
rated at 10 hp. by one manufacturer may be capable of develop- 
ing 10. to 25 per cent, more power than an engine of the same 
rating by another manufacturer. The purchaser should insist 
on a definite statement as to the actual brake horsepower which 
the engine is capable of developing. The method of obtaining 
the brake horsepower of an engine was explained in Chapter II. 

Installation of Gas Engines. — It is usually best to locate a 
gas engine in a separate room. The room should be well-lighted 
and ventilated, free from dirt and dust and large enough so 
that there is sufficient space for easy access to any part of the 
engine so as to facilitate starting, oiling and inspection of all 
parts. 

In connection with gasoline and oil engines, the fuel tank 
should be located outside the building and preferably under- 
ground. In any case the tank must be lower than the pipe to 
which it is connected in the engine room. 

As the mixture of fuel and air is ignited inside the engine 

8 



114 FARM MOTORS 

cylinder, the resulting explosion produces a shock of considerable 
magnitude on the mechanism, which in turn is transmitted to 
the foundation. The foundation should be as solid as possible. 
If the engine is to be set on a wood floor, it is usually well to lay 
long timbers on or under the floor and at right angles to the 
joists. If the foundation is to be built of brick or of concrete 
it should be sufficiently heavy and should be separated from the 
walls of the building, so that vibrations caused by the engine 
will not affect the building or surrounding buildings. If the 
engine has to be located over another room it is best to place the 
engine in a corner and near the wall. 

The method of constructing foundations for steam engines was 
explained in detail in Chapter IV. The directions given there 
apply also to gas engines. 

If the engine is to be connected to the machines to be driven 
by belt drive, the driver and the driven should be placed far 
enough apart, that the required power can be transmitted without 
running the belts too tight. A distance between pulleys equal 
to about eight times the size of the larger pulley will usually give 
good results. Open belts are preferable to crossed belts and 
should be used whenever possible. 

The exhaust piping should be as straight and as short as pos- 
sible. The exhaust gases should always be discharged out of 
doors, as the fumes are poisonous. Some engines are provided 
with exhaust mufflers (Fig. 71) which can be located near the 
engine. As a rule, it is better to locate the muffler outside the 
building. Engines should never exhaust into a flue or chimney. 

The air supply can be taken from the room in which the engine 
is placed or from the outside. In all cases a screen should be 
placed over the air pipe. 

Instructions for Operating Gas Engines. — Before an engine is 
started for the first time, all the working parts should be care- 
fully examined and nuts and other fasteners properly tightened. 
The electrical connections should then be gone over and the spark 
plug or spark points removed from the cylinder and tried. 

The operation and economy of a gas engine is greatly influenced 
by the proper timing of the valves and by the point of ignition. 

The exhaust valve should open before the end of the power 
stroke. This is necessary to prevent loss of power when the 



GAS AND OIL ENGINES 115 

piston starts on the exhaust stroke. The exhaust valve should 
begin to open when the crank is at an angle of from 20° to 40° 
before the outer dead-center. The time of opening of the exhaust 
valve must be earlier for high-speed than for slow-speed engines. 

The exhaust valve should remain open until the crank has 
turned 3° to 8° beyond the completion of the exhaust stroke. 

The suction stroke follows the exhaust stroke, and, in order 
to prevent the mixing of the fresh charge with the burnt gases, 
the inlet valve should open about 3° (crank rotation) after the > 
exhaust valve closes. The time of closing of the inlet valve should 
be after the crank has turned 10° to 25° beyond the completion 
of the suction stroke. 

The setting of the gas-engine valves so that they will open and 
close at the proper time, can be accomplished by adjusting the 
length of the valve push rods or by changing the timing of the 
cam gears. The exact setting of the valves will depend upon the 
engine speed, and upon the fuel used. 

Ignition should be timed to suit the fuel, the compression and 
the speed of the engine. 

In order that the entire mixture may be ignited and burning at 
the beginning of the power stroke, it is necessary to have the 
spark advanced; that is, the point of ignition must occur earlier 
than the beginning of the power stroke. 

Proper ignition can best be determined by an indicator (Fig. 1). 
The experienced operator can set the spark very nearly at the 
proper place by the sound of the engine. For the inexperienced 
operator the following approximate rules should prove of value : 

For jump-spark system, turn crank and set spark mechanism 
so that ignition will occur, 5° ahead of dead-center, for every 
100 r.p.m. of the engine speed rating. 

For the make-and-break system, advance spark approximately 
8° for every 100 revolutions of engine speed rating. 

As an illustration of the application of the above rule, calcu- 
late the spark advance for a stationary engine operating at 
350 r.p.m. If the engine has make-and-break ignition system, 
ignition should take place when the crank is at a position of 28° 
before dead-center. In case a jump-spark system is employed, 
the spark should occur when the crank is at a position of about 
17K° before dead-center. 



116 FARM MOTORS 

The gas engine is not self-starting, as is the steam engine when 
steam is turned on. The reason for this is that the explosive 
mixture of fuel and air must be taken into the cylinder and com- 
pressed before it can give up its energy by explosion. It is, 
therefore, necessary to set the engine in motion by some external 
means not employed in regular operation, before it will pick up 
the normal working cycle. Engines under 20 hp. are usually 
started by hand. This is done by disconnecting the engine 
from its load and turning the flywheel by hand for a few revolu- 
tions. If everything is in good condition an engine should start 
with two or three turns of the flywheel and should continue to 
run after the first explosion. An easier method of starting gaso- 
line engines is to set the engine at the end of the power stroke, in- 
ject some gasoline into the cylinder through a priming cock, turn 
the flywheel backward against compression as far as possible and 
then quickly trip the igniter. 

As it is difficult to pull over an engine by hand against com- 
pression throughout the whole stroke, some engines are provided 
with a starting cam, which can be shifted so as to engage the 
exhaust valve lever. This relieves the compression while crank- 
ing, as the exhaust port is open during the first part of the com- 
pression stroke. After the engine speeds up the starting cam is 
disengaged. 

Gas engines larger than 25 hp. are usually started with com- 
pressed air. If the engine consists of two or more cylinders, 
this can be accomplished by shutting off the gas supply to one 
of the cylinders and running this cylinder with compressed air 
from a tank, in the same manner as a steam engine is operated 
with steam from a boiler. As soon as the other cylinders pick 
up their cycle of operations the compressed air is shut off and 
fuel with air is admitted to the cylinder used in starting. With 
large gas engines of only one cylinder, the compressed air is ad- 
mitted long enough to start the engine revolving, when the com- 
pressed air is shut off and the mixture is admitted. The air 
supply for starting is kept in tanks which are charged to a pres- 
sure of 50 to 150 lb. by a small compressor, driven either from 
the main engine shaft, or by means of an auxiliary small engine. 

In starting a gas engine the following steps should be taken, 
preferably in the order given : 



GAS AND OIL ENGINES 117 

1. The fuel supply should be examined. Cases have been 
known in which an operator spent considerable time hunting for 
faults in the ignition system, valve setting, etc., when an examina- 
tion of the gasoline tank would have revealed the fact that it was 
empty. 

2. The ignition system should be tried by closing the switch 
disconnecting the end of one of the wires and brushing it against 
the binding post to which the other wire is attached. A good 
spark should have a blue-white color. If the spark produced is 
weak, the ignition system should be put in the proper condition. 

3. The lubricators and grease cups should be filled and ad- 
justed, so that the proper amount of oil is delivered to all bear- 
ings and moving parts. 

4. The load should be disconnected from the engine by means 
of a friction clutch or similar device, the lubricators turned on, 
the spark retarded to the starting position, and the starting cam 
moved into place. 

5. The engine is now ready for starting by either of the methods 
previously explained. In cranking, always pull up on the crank. 

6. As soon as the engine picks up, disengage starting cam, turn 
on cooling water, advance spark to running position and throw 
on the load by means of the clutch. 

7. Adjust fuel supply so that the engine carries its load with 
the cleanest possible exhaust. 

To stop an engine, the fuel valve is closed, the ignition-system 
switch is opened, the lubricators and oil cups are closed and the 
jacket water is turned off. In cold weather the water should be 
drained from the engine jackets to prevent freezing. The prac- 
tice of draining the jackets is also advisable in moderate weather, 
as this tends to clean the jacket from the. deposit of sediment. 
Before leaving the engine it should be cleaned, all parts examined 
and put in order ready for starting up. 

Causes of Gas Engines Failing to Start. — Failure to start may be 
due to one or more of the following causes : 

1. Ignition System Out of Order. — This may be caused by the 
switch being left open, by a loose terminal, by a disconnected 
wire, by a broken wire the insulation being intact, by the ignition 
battery being weak if a battery is used, and by poor timing or 
wrong connections if a magneto is employed. Other causes of 



118 FARM MOTORS 

faulty ignition are due to timer slipping on the shaft, to a short- 
circuit in the ignition system, to carbonized or broken spark 
points, to poor timing of the points of ignition. In the case of 
the jump-spark system, ignition will also be prevented if, the 
points on the spark plug are too far apart, the spark plug is dirty 
or broken, the insulation on secondary wires is poor, induction coil 
windings are broken or short circuited, vibrator of induction coil 
is not properly set. 

2. An engine will not start if the mixture contains too much 
or too little fuel. 

In very cold weather a gasoline engine may give trouble by the 
fuel not vaporizing. This can best be remedied by filling the 
jackets with hot water. Do not bring a flame near the carburetor 
or gas supply pipe. This is sometimes recommended for start- 
ing in cold weather, but the practice is a dangerous one. 

Improper mixture may be caused by slow cranking, in which 
case the hand placed over the air inlet will often start the engine. 
Extra priming of the carburetor may also aid in starting, pro- 
vided care is taken not to flood the engine with fuel. 

3. Supply pipes clogged. 

4. Dirt or water in the fuel. 

5. Pump or carburetor out of order. 

6. Water in carburetor. 

7. Water in the cylinder due to leaky jacket. 

8. Inlet valve poorly set or not operating due to broken valve 
stem, weak or broken spring, valve sticking or broken. 

9. Poor compression due to leaky or broken piston rings, 
improper seating of valves, or to other leaks from the cylinder 
to the outside. 

10. If the exhaust pipe or muffler is clogged, the engine will 
fail to start. 

In any of the above cases the remedies are self-evident. 

Causes of Motor Failing to Run. — A motor will sometimes start,. 
but will soon afterward slow down and stop. This may be due 
to: 

1. Fuel tank being empty or fuel pipe becoming clogged. 

2. Poor or insufficient lubrication, which may cause the seizing 
of the piston or of the bearings. 

3. Wire being jarred loose from its terminal, timer slipping on 



GAS AND OIL ENGINES 119 

shaft or to some other fault in the ignition system, such as weak 
cells, or vibrator or induction coil becoming stuck. 

4. Engine carrying too great a load. 

Care of a Gas Engine. — It is best to keep one man responsible 
for the care of an engine and in so far as possible confine the 
operation to one man. The engine should be kept clean and 
all the parts should be examined frequently- to see that everything 
is in the best working order. 

If an engine runs well at no-load but will not carry its rated 
load, this may be due to: poor compression, poor fuel, defective 
ignition, poor timing of ignition, incorrect valve setting, incor- 
rect mixture, leaky inlet or exhaust valves, too much friction at 
bearings, or to engine being too small for the rated load. 

The operator usually can tell whether the correct mixture 
is being admitted into the cylinder by watching the exhaust. 
Black smoke issuing from the exhaust pipe means that the mix- 
ture is too rich in fuel. This should be remedied by decreasing 
the amount of fuel supplied or by increasing the air supply. 
Insufficient fuel in the mixture, as explained in the section on 
" C ar buret or s," will cause the engine to miss explosions and may 
even cause back-firing. 

Premature ignition, often called preignition, is due to the de- 
position of carbon and soot on the walls of the cylinder, the com- 
pression being too high for the fuel used; by overheating of the 
piston, exhaust valve, or of some poorly jacketed part. 

Deposition of carbon on the cylinder walls is usually caused 
by the use of either an excessive amount or a poor quality of 
lubricating oil. This will not only cause preignition, but may 
also impair the action of the valves, igniter and piston rings. 
Carbon deposits will also be produced if the mixture is too rich. 

Insufficient lubrication may result in abrading surfaces of 
piston and cylinder. 

It is well not to economize when buying gas-engine cylinder 
oil. Due to the high temperatures developed inside the engine 
cylinder and to the absence of moisture, a cylinder oil should be 
selected which is light and thin, which will withstand high tem- 
peratures and will leave no carbon deposits. A cylinder-lubricat- 
ing oil well-suited for steam-engine use will not do at all for gas- 
engine cylinder lubrication. 



120 FARM MOTORS 

For the bearings and other wearing parts outside the cylinder, 
a good grade of machine oil will be found satisfactory. 

A blue smoke at the exhaust indicates that too much cylinder 
oil is being used. 

Pounding in gas and oil engines is either due to preignition, the 
causes of which were outlined above, to lost motion in some 
bearing of the engine, or to the engine being loose on its 
foundation. ' 

In the case of oil engines using a water spray with the fuel, too 
little water will result in preignition and consequent pounding. 
This should be remedied by supplying more water with the fuel. 
Too much water will be indicated by white smoke issuing from 
the exhaust pipe. 

Iii the case of a gasoline engine, white smoke at the end of the 
exhaust pipe usually indicates water in the gasoline, which may 
be due to a leaky jacket or to some other cause. 

In regard to the temperatures of the jacket water, this depends 
on the compression carried and on the size of the engine. With 
small engines of the hopper-cooled type the jacket temperature 
is near the boiling-point of water. Ordinarily a temperature of 
about 150°F. will give good results. It is advisable to use cooling 
water over and over again, since after several circulations 
through the jackets, the impurities contained in the water will 
have been precipitated. 

Problems: Chapter V 

1. What is an internal-combustion engine and how does this form of motor 
differ from the steam engine? 

2. Explain, using clear sketches, the Otto gas-engine cycle. 

3. Show the difference in construction and in action between the four- 
stroke cycle and the two-stroke cycle gas engine. Use clear sketches to 
illustrate the important working parts. 

4. What is gasoline and how does this fuel differ from kerosene? 

5. What is denatured alcohol? How do the calorific values of alcohol and 
of gasoline compare? 

6. Discuss the use of alcohol as a fuel for internal-combustion engines. 

7. Give a clear sketch, showing the important parts of a gasoline engine. 
Name all parts. 

8. Why is proper carburetion necessary for the economical and reliable 
operation of a gasoline engine? 

9. Sketch and describe some form of mixer valve. When are mixer valves 
used? 



GAS AND OIL ENGINES 121 

10. Sketch and describe a concentric-type float-feed carburetor and 
explain in detail the function of the auxiliary air valve. 

11. Describe in detail carburetors shown in Figs. 81 and 82. 

12. Discuss carbureting kerosene and the heavier oils. 

13. Sketch and explain some form of air-cooled engine. What limits the 
size of the air-cooled engine? 

14. Give directions for preparing a non-freezing mixture to be used in a 
water-jacketed engine. 

15. Explain with clear sketches the make-and-break system of ignition. 

16. Explain, using sketches, the jump-spark system of ignition. 

17. What is the difference between the coils used in the make-and-break 
and in the jump-spark systems of ignition? 

18. Give wiring diagrams for a one-cylinder make-and-break ignition 
system, operated with dry cells to start and magneto to run on. 

19. Give wiring diagram for a one-cylinder jump-spark ignition system 
operated with a dry battery to start and a magneto to run on. 

20. Explain three methods for lubricating gas engines. 

21. Describe two systems of governing gas engines. 

22. Describe ten uses to which the stationary gasoline engine may be put 
by a .farmer. 

23. What should be considered when selecting a gas engine for farm use? 

24. Give directions for installing a gasoline engine. 

25. Prepare a diagram which should show the proper crank positions 
at which the valves should open and close. 

26. What governs the point of ignition? Give approximate rule for 
setting an engine operated with the make-and-break ignition system so that 
the spark will occur at the proper time. 

27. Give method for starting by hand, easily, a gasoline engine of 10 hp. 
capacity. 

28. Explain causes for gas engine failing to start. 

29. Explain the difference between preignition and back-firing. 

30. Give directions for operating a stationary gas or oil engine. 



CHAPTER VI 
AUTOMOBILES 

Types of Automobiles. — An automobile can be propelled by a 
steam engine, by an internal-combustion engine, or by an electric 
motor with current secured from storage batteries. 

The majority of modern automobiles are propelled by internal- 
combustion engines using gasoline as fuel. 

Steam and electric automobiles operate more quietly, are more 
flexible, and can be more easily controlled than gasoline auto- 
mobiles. Then, the electric car has the additional advantage 
of cleanliness and ease of starting, while the steam automobile 
has a greater range of power and is best-adapted for climbing 
hills. 

To offset the above advantages, electric cars are more expensive 
to operate, and can be run only for short distances without a fresh 
charge of electricity. They are, therefore, used mainly in cities 
and in other places where facilities are available for the charging 
of storage batteries. 

The steam automobile requires considerable time to start after 
a long stop, as steam must be generated in the automobile boiler 
before the engine will start. The steam automobile must also 
have greater skill in operating, as constant attention must be 
given to the fuel and the water supply. 

The gasoline automobiles possess the advantage that they are 
manufactured in many different types and designs, and can be 
secured at a great variety of prices from several hundred up to 
many thousand dollars per car. Repair parts can also be secured 
more easily for gasoline cars than for any other type of auto- 
mobile. The gasoline automobile is more economical than the 
steam or the electric car and is usually provided with a fuel supply 
of sufficient quantity to propel the car several hundred miles. 

The disadvantages of the gasoline automobile are that it is 
not self-starting, lacks overload capacity, must be provided with 
a clutch, as a gasoline motor will not start under load, and must 

122 



AUTOMOBILES 123 

be built with a complicated system of gears for changing speed 
and for reversing. 

This chapter will be devoted mainly to the consideration of the 
gasoline automobile, as steam and electric automobiles are seldom 
used in rural communities. 

Essential Parts of a Gasoline Automobile. — The essential 
parts of an automobile are : 

1. Power plant, which consists of an internal-combustion 
engine and its auxiliaries, such as the fuel system, carburetor, 
ignition system, cooling and lubricating systems, and starting 
systems. 

2. Friction clutch, for disengaging the engine from the propel- 
ling gear. 

3. Transmission mechanism, for speed-changing and for 
reversing. 

4. Differential or compensating gear, the purpose of which is 
to allow one drive wheel to revolve independently of the other, 
this being necessary when turning corners. 

5. Front and rear axles. 

6. The frame which supports the power plant, transmission 
system, and body of the car. The frame is attached to springs 
which in turn are attached to the axles. The springs are built 
up from a number of broad and thin leaves. 

7. Control system, which is made up of the steering mechanism 
as well as of the hand levers and foot pedals for controlling the 
spark position, carburetor throttle, clutch and transmission 
gearing. 

8. Body, top, fenders, hood, dash, running board, front and 
rear wheels, tires, lighting system, tool chest, tools, wind shield, 
speedometer and odometer for showing speed per hour and total 
distances, alarm and similar equipment and accessories, which 
are found on the majority of automobiles. 

Automobiles are required by law to carry two lights in front 
and one rear, or tail light. The tail light is for the purpose of 
preventing rear-end collisions. 

The term chassis is applied to the car with the body and ac- 
cessories removed (Figs. 118 and 119). The chassis shown in 
Fig. 118 is an automobile chassis and the power is transmitted 
from the motor to the rear axle by means of a shaft drive. In the 



124 



FARM MOTORS 



case of auto trucks the power from the motor to the axle is trans- 
mitted by worm or chain drive (Fig. 119). 




Automobile Motors. — Automobile motors are usually of the 
multiple-cylinder vertical types of internal-combustion engines 



AUTOMOBILES 



125 



which operate on the Otto four-stroke cycle. The motor is 
located in the front of the automobile frame, for accessibility and 
for the purpose of balancing the weight in the rear part of the 



car. 



The earlier automobiles employed one-cylinder engines, but 
the modern automobile motor consists of four, six, eight, or 




twelve vertical cylinders, as multi-cylinder machines start easier, 
operate more smoothly, run with less vibration, and have a 
wider range of power and speed. 

In the case of four- and six-cylinder motors, all the cylinders 



126 



FARM MOTORS 





1 


\ 














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. 


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w^aT ' • 


,i:|p3i||r;'-;: : ^; ; '--::"; ; -' :; v.' 




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Fig. 120. — Four cylinder automobile motor. 




Fig. 121. — Cylinders at an angle of 90°. 



A UTOMOBILES 



127 



are usually located on one side of the crankshaft (Fig. 120). 
Eight- and twelve-cylinder motors are arranged with the cylinders 
in two rows. Eight-cylinder machines are usually set as shown 




Fig. 122. — Automobile motor, cylinders cast singly. 




Fig. 123. — Motor with cylinder en-bloc. 

in Fig. 121 with the cylinders at an angle of 90°. The twelve- 
cylinder motors are usually set with the cylinders at an angle of 60°. 
Automobile motor cylinders are cast singly (Fig. 122), or 
en-bloc, which means that several cylinders are cast in one piece 



128 



FARM MOTORS 



(Fig. 123). The simple cylinder casting is light in weight, can be 
easily repaired, and is better adapted for the thermo-syphon 

system of cooling. The en-bloc 
motor is more rigid, occupies less 
space, and is more commonly used 
on modern automobiles. 

Automobile motors are most 
commonly water-cooled and are 
provided with radiators (Fig. 124) 
for the purpose of cooling the 
water after it has absorbed heat 
from the cylinder walls. There 
are two systems of cooling auto- 
mobile motors: 

1. The thermo-syphon water-circulation system (Fig. 125) 
depends upon the fact that water rises when heated. The 




Fig. 124. — Automobile radiator. 




Fig. 125. — Thermo-syphon water-circulation system. 



system does not require a force pump to circulate the water. The 
water enters the cyliDder jackets at A. -Upon becoming heated 
by the explosions going on within the cylinder of the engine, the 
water rises to the top, entering the pipe B and passing into the 



AUTOMOBILES 



129 



radiator at C, where it is brought into contact with the larger 
cooling surface D. On being cooled, the water becomes heavier 



* 


#\ &. 


""'X 






s> ^_ — ~ 


r 7CW,^ 


1 


► .- *J 


; - *^ 


. Tatars, ■ -~ ; - 



Fig. 126. — Air-cooled automobile motor. 



and sinks to the bottom of the cooling system, to enter the cylin- 
der once more and to repeat its circulation. The cooling action 
is further increased by a belt-driven 
fan (F) which draws air through the 
radiator spaces. 

2. The forced circulation system 
depends upon a pump, driven by the 
engine, to keep the water in constant 
circulation through the engine jacket 
and radiator. This system is more 
positive in its action and is not in- 
fluenced by obstructions as is the 
thermo-syphon system. 

In one successful type of auto- 
mobile, the cylinders are cast simply 
with ribs and are air-cooled. The circulation of the air is pro- 
duced by means of a fan in the motor flywheel (Fig. 126). 

Three types of valves are used on automobile motors. These 
are the poppet, the sleeve and the rotary. 




Fig. 127.- 



Motor with poppet 
valves. 



130 



FARM MOTORS 



The poppet valve (Fig. 127) is most commonly used and is 
similar to the valves used on stationary gasoline engines. 

Fig. 128 illustrates the fundamental parts of the sleeve-valve 
type of motor. The sleeves slide up and down between the main 




12 



1. Cylinder. 

2. Water- jacketed cylinder 

head. 

3. Spark plug. 

4. Inner sleeve. 

5. Outer sleeve. 

6—7. Port openings in sleeves. 

8. Priming cup. 

9. Oiling grooves in sleeves. 

0. Port opening in cylinder. 

1. Connecting-rod operating 

outer sleeve. 
Connecting-rod operating 
inner sleeve. 



13. Fly wheel. 

14. Oil trough adjusting lever 

connected to throttle. 

15. Lower part of crank case, 

containing oil pump, 
strainer and piping. 

16. Oil scoop. 

17. Adjustable oil troughs. 

18. Crank shaft. 

19. Crank-shaft bearing. 

20. Starting clutch. 

21. Silent chain drive for 
magneto shaft. 



22. 



Silent chain driving sprock- 
et for electric generator 
(on 4-cylinder models). 

Silent chain drive for 
eccentric shaft. 

Eccentric shaft. 

Connecting rod. 

Bearing for eccentric shaft. 

Piston. 

Piston rings. 

Cylinder-head ring (junk 
ring) . 



Fig. 128. — Sectional view of Stearns-Knight four-cylinder motor. 

engine piston and the cylinder walls. The various parts are 
named in Fig. 128. 

The rotary form of valve (Fig. 129) is little used. This type of 
valve consists of a slotted cylinder which, when rotating, opens a 
passage for the gases. 



AUTOMOBILES 



131 




Fig. 129.— Motor with rotary 
valves. 




Fig. 130.— Tee-head cylinder. 





Fig. 131.— Ell-head cylinder. 



Fig. 132.— Valves-in-the-head 
cylinder. . 



132 



FARM MOTORS 



Automobile motors with poppet valves are built in three forms : 

1. The tee-head form (Fig. 130) with valves on opposite sides. 
This type of motor usually has two camshafts for operating 
the valves, but allows the use of larger valves. The com- 
pressing chamber is irregularly shaped in this type of motor. 

2. The ell-head motor (Fig. 131). This form of motor has 




Fig. 133.— Cone clutch. 

both valves on the same side of the cylinder and these valves are 
operated by a single camshaft. 

3. The valve-in-the-head type of motor (Fig. 132). This type 
of motor has a very compact compression chamber, but is more 
noisy than the other types on account of the rocker arms and 
push rods. 

Clutches. — The clutch is a device used for connecting the 
engine shaft to, and disconnecting it from, the propelling gear of 



AUTOMOBILES 



133 



the car. Clutches depend upon the frictional adhesion between 
surfaces and are of the following types : 

1. The cone clutch (Fig. 133) consists of a leather-faced cone C 
which is pressed by the spring S against the inside of a tapered 
rim of a flywheel (W). 

2. The multiple-disk clutch (Fig. 134) depends on its action 
upon the friction between disks. Alternate disks are fastened to 
the driving and driven parts. The disks marked A are fastened 




Fig. 134. — Multiple-disk clutch. 

to the engine shaft and those marked B connect with the mechan- 
ism to be driven. If the clutch runs in a bath of oil, it is called a 
wet-disk clutch. A spring is employed to hold the disks in con- 
tact when the clutch. is in action. 

3. The expanding clutch has an annular ring which, by expand- 
ing, connects the driving and driven shafts. This type of clutch is 
seldom used. 

Clutches are not necessary on automobiles which are propelled 
by steam engines or by electric motors, as the supply of steam or 



134 



FARM MOTORS 



of electricity is generated outside the motors proper and can be 
varied to suit the requirements of speed and load. 

Transmission Gears. — The speed of an internal-combustion 
engine and its direction of rotation cannot be varied to meet the 
requirements of a self-propelled vehicle. This necessitates the 
introduction of a speed-changing and reversing-gear mechanism, 
so that different speed ratios can be secured between the engine 
and the drive axle. 

From the definition of power (Chapter II), it is evident that a 
motor of a given power, in order to overcome increasing resist- 
ance, must propel the car at a less speed. This means that the 
speed of the car must be reduced, by shifting the speed-changing 
gears, when the automobile must climb hills or overcome other 
obstructions incidental to the road conditions over which the car 




xdj v^y 

Fig. 135. — The progressive sliding-gear transmission system. 

is operated. Before shifting the gears of the transmission system, 
the friction clutch should be thrown out. 

Transmission gears are of four types: namely, the progressive 
sliding gear, the selective sliding gear, the planetary gear, and 
the friction drive. 

The Progressive Sliding-gear Transmission System. — The 
change of gears is carried on in progressive steps. Fig. 135 
illustrates a progressive transmission system. A is the driving 
shaft, which derives its power from the motor and through the 
friction clutch. B is the driver or propeller shaft which trans- 
mits the power to the rear axle. The gears C and D are fastened 



A UTOMOBILES 



135 



together and can be slid by means of a lever L along the main 
shaft, which is square. If D on the main shaft is shifted so 
that it is in mesh with E on the countershaft and the shaft A 
is rotated, the shaft B will rotate in the same direction but 
more slowly. If the gears C and D are shifted so that C will 
engage K, the countershaft F will turn the shaft B at a slower 
speed than when D and E were in mesh. If the gears C and D are 
shifted so that C meshes with R, A and B will revolve in the oppo- 
site directions, thus propelling the car backward. If the gears C 
and D are moved to the left until the lugs on D and on H engage, 
shafts A and B will turn as one shaft and the car will be propelled 
at the high speed forward. 



/^v 




\^/ ^/ \^r 

Fig. 136. — The selective sliding-gear transmission system. 



The Selective Sliding-gear Transmission System. — The de- 
sired speed can be secured without shifting through other gear 
positions as in the progressive system. This system is used on the 
largest number of automobiles. 

In Fig. 136, A is the driving shaft, B the driven shaft. S and 
L are slides carrying yokes that move the wheels D and K. All 
the wheels on the countershaft are fast to the shaft. A lever is 
arranged for shifting either S or L and for allowing the various 
gears on the shaft B to mesh with those on the countershaft. 
This system is commonly arranged for three speeds forward and 
one speed reverse, but can be modified to give any number of 



136 



FARM MOTORS 



speeds for forward and for reversing. Fig. 137 illustrates 
selective transmission system and multiple-disk type clutch. 




Fig. 137. — Transmission system and clutch. 




Fig. 138. — Planetary transmission system. 

The Planetary Transmission System. — In the planetary system 
of transmission the speed changes do not depend upon the 



AUTOMOBILES 137 

shifting of gears, but clutches or brakes are employed for holding 
certain wheels in position. The drive is positive, and the gears 
are always in mesh. 

The planetary system is particularly well- adapted for high 
speeds, as the entire system is clamped solidly and revolves with 
the motor crankshaft as a single mass, when the car is propelled 
at high gear; no gears are turning idly, and the transmission 
system, by its weight, serves to steady the rotation of the motor. 

The objections to the planetary system are that it provides 
only two forward speeds and one reverse speed, and is not efficient 
on low and reverse speeds, on account of the power absorbed by 
fhe friction between the clutches and the gears. This system is 
used mainly on small automobiles. 

A planetary transmission system, which is used in . a Ford 
automobile, is illustrated in Fig. 138. Brakes applied by means 
of foot pedals are used for holding certain of the gears stationary 
for low speed and for reverse. For high speed forward, the 
friction clutch, which is of the multiple-disk type and is part of 
the planetary system, connects directly the driving and driven 
shaft. 

The Friction Drive. — The friction-drive form of transmission is 
illustrated in Figs. 139 and 140 and depends upon the friction 
between rolling surfaces. 

A flat-faced disk A is carried on an extension of the engine 
shaft. The other part of the transmission consists of a fiber-faced 
friction wheel B which can be slid along the shaft S and brought 
into f rictional engagement with the disk A . The power is trans- 
mitted from the shaft S to the driving wheels by a chain (C) and 
sprocket wheel, or by bevel gears and a propeller shaft. As the 
wheel B is moved, by the aid of the lever L, nearer the center of the 
disk A, the shaft S rotates more slowly; shifting the wheel B 
nearer to the outer edge of the disk A, Sis rotated faster. Sliding 
B to the right of the center of A reverses the direction of rota- 
tion of the shaft. 

The chassis of an automobile with friction drive is illustrated 
in Fig. 140. 

The friction drive is the simplest of all forms of transmission, 
is inexpensive, is more silent and permits the propulsion of the 
car, at an unlimited number of speeds in either direction. The 



138 



FARM MOTORS 




Fig. 139. — Friction drive. 




Fig. 140. — Chassis of automobile with friction drive. 



AUTOMOBILES 



139 



disadvantages of this system are that the drive is not absolutely 
positive, that there is a loss of power due to slipping, that fric- 
tional surfaces wear rapidly, and that the system cannot be prop- 
erly enclosed. The friction drive is used mainly on light cars. 
Differentials for Automobiles. — When an automobile turns a 




Fig. 141. — Bevel-gear differential. 

corner, the drive wheel on the outside of the curve must turn 
faster than that on the inside. If the two drive wheels, which are 
the rear wheels, were rigidly connected, one would have to skid 
or slip when turning a corner or when going over an obstruction; 
this would throw a great strain on the front axles and wheels with 



140 



FARM MOTORS 



consequent wear on the tires. The differential, sometimes called 
a compensating or equalizing gear, allows one drive wheel to 
move ahead of the other when turning a corner or when over- 
coming resistances due to the unevenness of the road, while at 
the same time both wheels are driven from the engine. 




Fig. 142. — Spur-gear differential. 

There are two types of automobile differentials, the bevel- 
gear type and the spur-gear type. 

The bevel-gear type of differential (Fig. 141) is most commonly 
used. The rear axle S is divided into two halves. Each half of 
the rear axle carries a drive wheel at its outer end and a bevel 



AUTOMOBILES 141 

gear (C or D) at its inner end. The two bevel gears C and D 
are connected by three or four differential or compensating 
pinions (B, B, B) which are placed at equal distances apart 
around the circle. These bevel pinions (B, B, B) are capable of 
rotating loosely on radial studs which are fastened at their outer 
ends to the casing or housing 0. Gear A is made to turn loosely 
upon the hubs of bevel gears C and D but is made fast to the 
casing or housing by means of bolts. The power from the 
engine is transmitted to the housing through the bevel gear P 
which meshes with gear A. The housing transmits this power 
through the small bevel pinions (B, B, B) to the bevel gears C 
and D, which are connected to the rear wheels or drive wheels. 

On a level road with both drive wheels rotating at the same 
speed, the housing with the gears and pinions will revolve as 
one mass and the small pinions, marked B, will remain stationary, 
In turning a corner, in meeting an obstruction, or in case one of 
the wheels slips, if the drive wheel attached to the bevel gear C 
must turn slower than that attached to gear D, the differential 
pinions (B, B, B) will revolve on their axes. The bevel pinions 
(B, B, B) act as balance levers, similar to the doubletrees or 
eveners on a team of horses, dividing the torque between the two 
bevel gears (C, D) and allowing the two drive wheels to run at 
different speeds. 

The spur-gear type of differential, now seldom used, is shown 
in Fig. 142. The power from the engine is transmitted to the 
housing through the bevel gear P, which meshes with the gear 
A. The housing transmits this power through the small spur 
pinions (B, B, B) to the spur gears C and D, which are connected 
with the drive wheels. The action of this differential is similar 
to the bevel-gear differential of Fig. 141. 

The relative positions of the transmission, the differential, 
and the driving wheels are illustrated in Fig. 143. 

Universal Joint. — Since the engine and the gearing are mounted 
on the frame of the automobile, while the driving wheels are 
connected to the frame by springs, automobiles with shaft drive 
must be provided with some flexible joint. The universal joint 
(Fig. 143), which consists of forked arms at the ends of shafts, 
and at right angles to each other, permits the lower end of the 
propeller shaft to move independently of the motion of the rear axle. 



142 



FARM MOTORS 



" Propeller shaft" (Fig. 143) is the term applied to the shaft 
which connects the transmission with the differential. 




It II 



Front and Rear Axles. — The front axles are of a construction 
which permits the wheels to pivot near the hub. With this 
construction there is not the tendency for the wheel to swing 



AUTOMOBILES 



143 



around when striking an obstruction in the road. The steering 
knuckles are a part of the front axle, on which the front wheels 
revolve. Steering arms are inserted in the knuckles and con- 
nect together with an adjustable tie-rod so that both knuckles 
turn simultaneously. A third arm attached to the left-hand 
knuckle connects the steering gear by means of the steering 
connecting rod. In Fig. 144 the various parts of the front 
axles are illustrated. Some front axles are constructed of heavy 
steel tubes, with dropped forged axle ends. The majority of 
automobiles are constructed with front axles which are drop- 
forged I-beam sections (Fig. 144). 

























'•Wk 




_ i ', c? boll 


ho 








F " K 








;*,v 4/ '^ r 


















Illll:, - 


arm 






■ 










%\ ■ 


ttabk 


stop " 






k1 


* ,/ 


-«- : . 




J^ 


Spi 


IL J-Bsarr 


center 




^**l 


■"- 


Sjfc 


^38 












1 


■''li.'t' 


















1 


\Hub.b?o 


% 




















H| 


i 


-?./'.'./ 


stable yake 




rod 







Fig. 144. — Details of front axle. 



The rear axle of the automobile carries the differential and the 
two rear wheels. In one type of rear axle, called the semi- 
floating type, the axles carry the entire load. In the full-float- 
ing axle the weight of the car is carried by a housing through 
which the axle passes. In the full-floating axle the shaft may 
be removed without disturbing the wheel or the differential. 

Steering and Control Systems. — Automobiles are steered by 
means of a hand wheel which is located on the top of the steering 
column. The steering gear operates on the front axle, through 
the steering connecting rod, and turns the knuckles and front 
wheels. The steering column (Fig. 145) usually contains several 
concentric tubes with connections to the alarm, the throttle 
control, the spark control, and the steering mechanism which 
reduces the motion of the steering wheel. 



144 



FARM MOTORS 



Sector 



Spark /ever 
/ Throttle lever 




Steering tube 



__^ Spark roc/ 



— Stationary tube 
— Throtf/e tube 



Steering gear 
hous/no ~-~ 




Pitman arm 



Fig. 145. — Steering gear. 



AUTOMOBILES 



145 



The worm-and-nut form of steering gear (Fig. 145) consists 
of a double-threaded worm attached to the hand wheel and two 
half nuts, one of which has a right-handed thread and the other 
a left-handed thread. If the steering wheel is turned, one of the 
half nuts moves up and the other down, thus turning the steering 
yoke and moving the pitman arm back and forth. The motion 
of the pitman arm is transmitted to the steering knuckles and 
front wheels. 

Another form of steering gear consists of a worm-and-worm 
gear (Fig. 146). The worm-gear shaft carries the pitman arm, 



For grease 




Fig. 146. — Worm-and-worm-gear steering mechanism. 

which transmits the motion of the steering wheel to the steering 
knuckles and to the front wheels. 

The spark and the carburetor throttle-control levers are usually 
located on top of the steering wheel (Fig. 145), but, in some few 
makes of cars, under the wheel on the steering post. The speed 
of the automobile motor is controlled by the throttle and spark 
levers. 

The largest number of cars are provided with two methods of 
throttle control, the band throttle-control lever on the steering 
wheel and a foot control of the throttle, commonly called the 

10 



146 



FARM MOTORS 



accelerator. The foot throttle-control lever is usually employed 
when shifting the transmission gears, as one hand is required to 
operate the gear-shifting lever while the other is engaged in steer- 
ing the car. The accelerator is also used when running an 
automobile through crowded streets. The hand throttle lever 
and the accelerator are interconnected, so that the accelerator 
will move up or down if the hand throttle lever is shifted. 

The control system (Fig. 147) includes a pedal for operating 




Emergency brake lever 

Muffler cut out* 

Fig. 147. — Automobile control system. 

the friction clutch, one for operating the service brake, a lever 
for operating the emergency brake, and a lever for operating the 
speed-changing and reversing gears of the transmission. 

The Ford automobile is controlled by three foot pedals and 
by one hand lever. The pedals operate the clutch, the reverse, 
and the service brake. The hand lever operates the clutch and 
the emergency brake. 

Brakes. — Automobile tires being made of rubber, the brakes 
are not applied to the wheel tires but to metal drums which are 
usually fastened to the rear wheels. Two brakes are employed. 
One brake, called the service or running brake, is operated 
by means of a foot pedal. The other brake, called the emergency 
brake, is operated by a hand lever and is intended for use only in 



AUTOMOBILES 147 

case the service brake fails or in case a very strong braking 
action is required. Automobiles, with the planetary system of 
transmission (Fig. 138), have the service-brake drum near the 
transmission mechanism. 

The braking effect can be produced by expanding the brake 
band or shoe within the brake drum or by contracting the brake 
shoe around the outside of the drum. 

The brake bands are usually covered on the rubbing side with 
an asbestos preparation, which can be replaced when worn out. 




Fig. 148. — Section of brake. 

The brakes in Fig. 148 consist of an external service brake 
and an internal emergency brake. 

Wheels and Tires. — Automobile wheels are made of wood or of 
metal. The wooden wheels are considered more flexible, but the 
metal wheels are lighter. 

Tires made of rubber are used to take up the road vibrations 
before they reach the car proper. 

The double pneumatic rubber tire is used on gasoline automo- 
biles, while the solid rubber tire is employed to a limited extent 
on trucks and on electric automobiles. The double automobile 
pneumatic tire consists of an inner rubber tube with a check valve 
to hold the air and an outer casing which protects the inner 
tube from wear. The outer casing is built up of strong canvas 
fabric covered with a tougher and denser rubber than the inner 
tube. 

Single-tube pneumatic tires, similar to bicycle tires, have been 
used to some extent on automobiles. Double tires are preferable 
on account of the security of their attachment to the wheel rim. 



148 FARM MOTORS 

In bicycles the single tire is practical as the danger of the tires 
rolling off the rim is averted by the inclination taken by the 
entire wheel when turning corners. 

The tread of automobile wheels is usually 56 in., measured 
from wheel center to wheel center when the tires touch the 
ground. 

Carburetors and Gasoline Feed Systems. — Automobile car- 
buretors are of the float-feed type and are usually of the 
forms described in Chapter V and illustrated in Figs. 78 to 81. 
Multiple-nozzle carburetors are adapted for high-powered 
automobiles. 

The carburetor throttle, as previously explained, can be con- 
trolled by the accelerator as well as by the hand throttle lever 
on the steering post. With the pressure removed from the 
accelerator, the carburetor throttle will close to the position set 
by a hand throttle lever. 

To meet the requirements of the lower grades of gasoline, 
automobile carburetors are often jacketed and the air supply is 
preheated by the exhaust gases. 

The concentric types of float-feed carburetor (Figs. 78, 80 and 
81) are much used, as the fuel level in the float chamber is not 
affected by the inclination of the car. A carburetor should be of 
the proper size for the automobile motor. If the carburetor is 
too large, the fuel economy and the engine capacity will be re- 
duced, as the air velocity through the mixing chamber would 
be too low to produce the proper mixture of air and fuel. A car- 
buretor too small for the engine it is to serve will chill on account 
of insufficient heat supplied by the entering air and this will 
also result in poor fuel economy and loss of power. 

The following systems are used for feeding fuel from the gaso- 
line tank to the carburetor : 

1. The Gravity-feed System. — The gasoline tank is placed above 
the level of the carburetor and the fuel flows by gravity. This 
system is simple, but when the fuel tank is placed under the 
seat, the pressure on the carburetor float valve is not constant, 
and, in ascending hills, the gasoline supply may become inter- 
rupted. Sometimes this difficulty is overcome by placing the 
fuel tank in the cowl, the space back of and above the engine. 

2. Pressure-feed System. — The fuel tank is placed at the rear 



AUTOMOBILES 149 

of the car and the gasoline is forced to the carburetor by pressure. 
The initial pressure is secured by an air pump, and after the 
engine is in operation the exhaust gases create the necessary 
pressure. A safety valve keeps the pressure within the required 
intensity. This system is positive and the fuel is supplied to the 
carburetor regardless of the position of the car, but the pressure 
interferes with the proper operation of the float. 

3. Vacuum-feed System. — The suction stroke of the engine is 
utilized to lift gasoline from the fuel tank to the auxiliary tank 
near the engine, from which the fuel flows to the carburetor by 
gravity. This system has all the advantages of the pressure- 
feed system and is more reliable. It is also superior to the 
gravity system in that the gasoline supply is independent of the 
position or location of the fuel tank. 

Ignition. — The jump-spark electric system of ignition (Chapter 
V) is employed. In some makes of automobiles, batteries are 
used for furnishing current in starting and magnetos supply 
electricity for ignition, after the motor has attained normal 
speed. This is called the dual system. 

The voltage of a magneto increases with its speed, and this 
makes it desirable to employ a battery for starting. 

The advantages of magneto ignition are positive action, low 
upkeep, and simplicity. Magnetos can be constructed so as not 
to require hand advance of the spark. Various types of low- 
tension and high-tension magnetos (Chapter V) are used for 
igniting the mixture in an automobile engine. 

In some makes of automobiles, two independent means of igni- 
tion are employed. 

Other makes of automobiles employ the high-tension dis- 
tributor system with batteries or a modification of this system, 
such as the Delco or the Atwater Kent system. 

Fig. 149 illustrates an ignition system for a four-cylinder auto- 
mobile engine which uses battery with master vibrator. The 
master vibrator, as previously explained, eliminates the neces- 
sity of adjusting the vibrators of four different coils, the master 
vibrator serving for all the cylinders. 

The disadvantages of the master-vibrator system result from 
the fact that a faulty adjustment of this vibrator, which serves 
all the coils, will throw the entire system out of order. With 



150 



FARM MOTORS 




Groyno[\ 

Fig. 149. — Ignition system with battery and master vibrator. 




0rour?2f^_ i J J i j 

Fig. 150. — High-tension distributor system. 



AUTOMOBILES 151 

vibrators on each of the coils, an imperfect adjustment of one 
vibrator, while decreasing the power of the engine, will not dis- 
turb the entire system. 

In some automobiles the high-tension distributor system, often 
called the synchronous ignition system, is used. This requires 
only one induction coil for all the cylinders. This system must 
be provided with an interrupter for the primary circuit and with 
a distributor to direct the discharge of the single coil to the spark 
plug of the several cylinders in rotation. The distributor and 
the interrupter are mounted together. The various parts of 
the high-tension distributor system are illustrated and named in 
Fig. 150. 

The At water Kent system is of the high-tension distributor 
type and operates with a primary or storage battery (Chapter X). 
The essential parts of the Atwater Kent system (Figs. 151, 152, 
153) are: 

1. A non-vibrator type of induction coil with primary winding, 
secondary winding, and electric condenser. This type of induc- 
tion coil produces only a single spark as the circuit is made and 
broken only once. 

2. A timer or contact-maker in the primary circuit. The 
timer is constructed so that the length of contact is independent 
of the engine speed. 

3. A high-tension distributor with as many contact points 
as there are cylinders. 

4. A governor which advances the spark as the speed increases. 
This feature of the Atwater Kent system eliminates the necessity 
of the spark control lever on the steering wheel; and the driver 
has to control only the carburetor throttle. The automatic 
spark-advance mechanism, the circuit-breaker or contact-maker, 
and the distributor are all carried by one vertical shaft. The 
point of ignition can also be hand- controlled by turning a sleeve 
beneath the timer. 

The Atwater Kent system works on the open-circuit principle, 
similar to that of door bells, and there is no danger of running 
down the batteries by leaving a switch closed. 

The Delco system is illustrated in Fig. 154. This system in- 
cludes starting, ignition, and lighting systems all combined in 
one. A motor-generator set performs the function of cranking 



152 



FARM MOTORS 




CONTACT MAKER 

Fig. 151. — Wiring diagram of the Atwater Kent system. 





Fig. 152. — Contact maker of the Atwater Kent system. 




Fig. 153. — Atwater Kent unisparker. 



^i 



AUTOMOBILES 



153 



the engine and of supplying electrical current for ignition, lighting, 
blowing the horn, and charging the storage battery. The motor- 
generator consists of a dynamo (Chapter X) with two field 
windings, and two windings on the armature with two commuta- 
tors and corresponding sets of brushes. This construction is 




made in order that the machine may work both as a starting 
motor and as a generator. The ignition apparatus is incor- 
porated in the forward end of the motor-generator. A combina- 
tion switch is used for the purpose of controlling the lights, the 
ignition, and the circuit between the electrical generator and the 
storage battery. 



154 FARM MOTORS 

For ignition the Delco system employs a non-vibrator type of 
induction coil with a timer in the primary circuit, and a dis- 
tributor. A governor for automatic spark advance similar to that 
of the Atwater Kent, but of different design, is employed. 

In Fig. 154, if button B is pulled out, the current for ignition will 
be supplied by the dry cells. By pulling button M , current will 
be supplied through wire A, if the generator is in operation, or by 
the storage battery through wire B. 

Automobile Lubrication. — The parts requiring lubrication are 
the main shaft bearings, crankpin bearings, wristpin bearings, 
camshaft bearings, timing gears, cams, cam-lifter guides, cylinder 
walls and all other moving parts, such as the yokes and ends of 
rods, and steering mechanism. ■ 

Transmission gears, differential, and axle bearings are lubri- 
cated with heavy grease, as these parts and their casings are not 
oil-tight. In cold weather it may be necessary to thin down the 
lubricant of the transmission, the differential and the rear axle. 
Wheel bearings should be packed with thin cup grease. 

Occasional oiling of the clutch will insure free shifting of the 
transmission gears. An engine oil mixed with graphite is often 
used for this purpose. 

The lubrication of the steering mechanism should receive 
careful attention. The worm housing should always be packed 
full of grease. 

Ball bearings and magnetos should be lubricated with vaseline. 

In several of the light automobiles the splash system of lubri- 
cation is employed. The lubricating oil is supplied to the 
crank case of the motor. The connecting rods dip into and 
splash the oil to the various parts of the engine. 

A combination of the splash constant-level system and force 
pump (Fig. 109, Chapter V) is used to a considerable extent. 
The circulating pump lifts the oil from a reservoir or pump below 
the main crank-case bottom. The oil passes through a sight 
feed or sight glass on the dash, so that the circulation can be 
observed by the driver, and to the various bearings. From the 
bearings the oil falls to the reservoir at the bottom of the crank 
case. The height of the oil in the crank case is such that the 
connecting rods give additional lubrication by splash. 

The selection of a high-grade lubricating oil is of great impor- 



AUTOMOBILES 155 

tance, if good service and low cost of automobile maintenance 
are desired. The oil charts in the manufacturer's instruction 
book (Fig. 155) should be carefully followed and the parts should 
be lubricated at the intervals indicated. The oil best suited 
for the various parts usually has been determined by automobile 
manufacturers, and their recommendations should be followed 
for the various makes of cars. 

If the lubricating oil is too light in body or if the piston rings 
are leaky, the oil will work into the combustion chamber, pro- 
ducing not only a loss of oil, but also carbon deposits on valves, 
cylinder walls, and spark plugs. 

An oil which is too heavy will not spread freely, and poor 
lubrication will result. 

Insufficient lubrication will be indicated by the overheating 
of the parts and by a metallic knock, and will result in cutting, 
scratching, twisting, or otherwise ruining the parts. 

An excess of oil is usually more harmful to the motor cylinder 
than to the other parts, where the burnt oil will cause carbon 
deposits. Too much cylinder lubrication is indicated usually 
by a bluish, smoky exhaust, but a clear exhaust is not always an 
indication that the motor is properly lubricated. 

Carbon deposits will result in preignition, sticky pistons, 
sticky valves, dirty spark plugs, and ultimate loss of efficiency. 
Too much lubrication of transmission, differential, or bearings 
will produce waste by the leaking of the lubricant at the joints. 

Automobile Starting Systems. — Automobile motors are started 
by hand-cranking or by some automatic starting device. Before 
the motor is cranked, the carburetor throttle lever on the steering 
wheel should be moved up to open the throttle. The spark 
lever should be shifted to the retard position, as failure to do 
this may result in the engine kicking back on account of back- 
firing. The gears should be thrown into neutral position (Fig. 
136). 

In cranking by hand, the crank- handle latch should be thrown 
back in order to free the crank. The crank should now be pushed 
in as far as possible and turned in the clockwise direction until it 
catches. The motor should start if the crank is given a quarter 
or a half turn in the right-hand direction. In cranking an engine, 
always set the crank so as to pull up. One should not bear 



156 



FARM MOTORS 




Fig. 155. — Lubrication chart. 
(For description see page 157.) 



A UTOMOBILES 157 



DESCRIPTION OF FIG. 155. 

1. Every 500 miles grease spring hanger, cup grease. 

2. Every 500 miles grease motor trunion, cup grease. 

3. Every 2000 miles remove front wheels and repack roller bearings with 
cup grease. 

4. Always keep motor oil reservoir well supplied with motor oil. 

5. Inspect the gauge. 

6. Every 500 miles grease spring shackles, cup grease. 

7. Every 500 miles grease drag link, both ends, cup grease. 

8. Every 500 miles grease steering gear crank, cup grease. 

9. Every 3000 miles remove plug in steering gear and fill with cup grease. 

10. Every 300 miles oil brake and clutch shaft, motor oil. 

11. Every 1000 miles fill universal joint, cup grease. 

12. Every 500 miles grease spring shackle, cup grease. 

13. Every 300 miles oil brake equalizer shaft,, motor oil. 

14. Every 1000 miles fill universal joint, cup grease. 

15. Every 500 miles grease spring seat bearing, cup grease. 

16. Every 500 miles grease rear axle outer bearing, cup grease. 

17. Occasionally fill differential case, use transmission oil. 

18. Every 500 miles grease spring hanger, cup grease. 

19. Every 200 miles oil fan shaft, motor oil. 

20. Every 300 miles grease king bolt, cup grease. 

21. Every 500 miles grease spring shackles, cup grease. 

22. Every 500 miles oil spark advance governor, above and below, motor 
oil. 

23. Every 300 miles oil generator bearings, front and rear, five drops 
motor oil. 

24. Every 300 miles grease starter gear bearing, cup grease. 

25. Every 500 miles grease speedometer swivel joint, cup grease. 

26. Every 500 miles inspect and fill to top of jack shaft, transmission oil. 

27. Every 500 miles grease spring shackles, cup grease. 

28. Every 500 miles grease torque hanger, cup grease. 

29. Every 500 miles grease front bearing, cup grease. 

30. Every 500 miles grease torque hinge, cup grease. 

31. Every 500 miles grease rear axle outer bearing, cup grease. 

32. Every 500 miles grease spring seat bearing, cup grease. 



158 



FARM MOTORS 



down on the crank. If the motor does not start after this is 
repeated three or four times, the cause of trouble should be 
determined before further cranking. 

Electric automatic starting devices are usually employed in 
modern automobiles. An electric self-starter consists of an 
electric generator for furnishing electricity, a storage battery, and 
an electric motor to crank the automobile engine. The electric 
starting system is also supplied with switches for the purpose of 
controlling the supply of current; with protective devices such 
as fuses or circuit-breakers to prevent the discharging of the 




Fig. 156. — Delco starting system. 

storage battery or damage to coils, motor, or lamps; with an 
electric regulator to maintain constant voltage for various speeds 
of engine, and with electric meters for the purpose of indicating 
the amount of current supplied by the generator to the storage 
battery, and for indicating how much current is being supplied 
by the battery for ignition, lighting, and starting. 

Electric starters are built in connection with the single-unit, 
the two-unit, or the three-unit system. In the single-unit system 
electric generator and motor are in one unit and this motor- 
generator is used for cranking the engine, for charging the storage 
battery, and for furnishing current to be used for operating the 
engine ignition system and for the automobile lights. In the two- 
unit system a separate motor which receives its current supply 
from a storage battery is used for cranking the engine. The 



AUTOMOBILES 



159 



electric generator supplies current for charging the storage battery 
and also for ignition and lighting. In the three-unit system a 
magneto furnishes current for the engine ignition system; a 
separate direct-current motor, supplied with current from a 
storage battery, is used for cranking; while the electrical generator 
is used only for charging the storage battery and for operating 
the lights. 

There are a large number of electric self-starters on the market. 
Only two types will be described in this chapter in order to 
illustrate the fundamental details.- 

The Delco system (Figs. 154 and 156) combines in one unit 
the starting motor, the electrical generator, and the ignition 




Fig. 157. — Three-unit starting system. 



system. The motor-generator of this system has been described 
in connection with automobile ignition. This motor-generator 
has the ignition apparatus in the forward end and is located on the 
right side of the engine. 

The arrangement of the various parts of a three-unit starting 
system is illustrated in Fig. 157. G is the electric generator, M 
is the starting motor, and I is the magneto for ignition. The 
starting, lighting and ignition features operate independently of 
each other. 

Mechanical starters are also used to a limited extent on small 
cars, but have been largely superseded by electric starters. Some 
mechanical starters utilize springs, which when released revolve 
the engine crankshaft. Other mechanical starters depend for 
their action upon a clamp, and are mainly hand-cranking devices 



160 FARM MOTORS 

with the driver remaining in his seat. In general, no mechanical 
starter will start an engine which cannot be started by hand. 

Automobile Lighting and Accessories. — Automobiles are 
lighted by kerosene, acetylene, or electricity. Electricity is 
coming into general use. Kerosene, when used, is placed in a 
side light or a tail lamp. 

Acetylene gas is generated by adding water to calcium carbide. 
The gas may be generated while the car is in operation, or may be 
bought in the compressed form in steel storage tanks under the 
name of 'prestolite. Prestolite gas is more commonly used. When 
the storage tank is exhausted, it is exchanged for a fully charged 
tank. Prestolite tanks are usually placed on the running board 
of the car. The acetylene gas may be lighted by a match or by 
an electric spark controlled from the seat of the operator. 

Electric lights are most popular. Electricity for illumination 
is usually secured from a storage battery. In the cars with 
electric starters, the storage battery is recharged from the gen- 
erator; in other cases the battery is recharged from an outside 
source. In some automobiles alternating-current magnetos 
furnish lighting current while the car is in motion. 

A car lighted with a battery charged from an outside source is 
equipped with a storage battery of 80 to 100 amp.-hr. capacity 
(Chapter X) which supplies current for illumination and for 
blowing the horn. This lighting storage battery is usually not 
used for engine ignition, unless the car is equipped with a dynamo 
to recharge the battery. When the storage battery is used for 
lighting, ignition, and starting its capacity should be at least 
90 amp.-hr. 

The accessories of a modern automobile are: lamps, speed- 
ometer for measuring the speed of the car in miles per hour, horn, 
tool kit, jack, tire tools and tire repairs, gasoline gage on dash, 
and mirror. 

Management of Automobiles.— Before an attempt is made to 
start an automobile, the operator should be certain that the fuel 
tank has sufficient gasoline, that the gasoline valve from the 
tank to the carburetor is open, that the lubricating system is in 
good working order, that the radiator is filled with clean water, 
and that the engine ignition system is working properly. In the 
case of a dual-ignition system the switch should be closed on the 



AUTOMOBILES 161 

battery side. The transmission gears should be thrown into 
neutral position (Figs. 135 and 136), and the emergency brake 
should be set. Before cranking the engine, the spark lever 
should be shifted to the retard position and the carburetor 
throttle lever should be advanced. 

The rules given in the discussion of starting systems should be 
followed in starting an automobile engine by hand-cranking. 
With electric self-starters, the starting pedal is pushed forward 
and down as far as it will go and is held down until the engine 
starts. As soon as the engine starts, the foot should be removed 
from the starting pedal. 

Easy starting may be obtained by throttling the air just as the 
engine stops, thus leaving a rich mixture in the motor. 

In extremely cold weather, or after prolonged standing of the 
car, it may be necessary to prime the carburetor or even to inject 
gasoline into each of the priming cups. 

When the engine starts, the spark lever should be advanced. 
To start the car, the emergency brake is released, the clutch is 
slowly disengaged while the transmission gears are thrown into 
slow gear forward, and the foot accelerator and spark lever are 
operated to take care of the increased load on the car. 

To stop an automobile, the motor is slowed down by removing 
the foot from the accelerator, the clutch is disengaged, the service 
brake is operated so that the car comes to a gradual stop, and the 
transmission gears are shifted into the neutral position. 

To stop quickly the operator presses on both foot pedals, 
releasing the clutch and applying the service brake, while apply- 
ing also the hand emergency brake. 

To reverse, the car is stopped by throwing the clutch out, thus 
disengaging the motor from the transmission; then the reverse 
gear is shifted and the clutch is thrown in slowly. 

In changing from low speed to intermediate or to high speed, 
the foot accelerator is released, the clutch is throw T n out, the 
gears are quickly shifted, the clutch is thrown in mesh, and the 
foot accelerator is adjusted for proper operation. 

In going down a long, steep grade the foot and emergency 

brakes should be used alternately in order to equalize the wear on 

the brakes. The engine is also used sometimes as a brake when 

descending steep hills, with the throttle closed, the spark off, and 

li 



162 FARM MOTORS 

the clutch engaged. The car runs the engine against compression, 
and the engine acts as a brake. By using the engine in this man- 
ner, the wear on the brakes is lessened. 

The low speeds are used in starting, in driving through bad or 
sandy roads and in climbing steep grades. 

To increase engine speed the carburetor throttle should be 
opened by the throttle lever on the steering wheel or by the foot 
accelerator and the spark advanced. 

In operating a car the clutch should always be thrown out 
before changing gears. No attempt should ever be made to 
engage the reverse gear until the car comes to a full stop. When 
the clutch is thrown in, the motor is connected to the propelling 
gear. The clutch should always be thrown in gradually in order 
that the motion of the motor shaft may be transmitted to the 
drive shaft without jarring. If the clutch is thrown in suddenly, 
the motor may stop or the mechanism of the car may be injured. 
The clutch should be thrown out when the automobile is to be 
slowed down, as this will reduce wear on the brake lining. The 
clutch should also be used for stopping the car, if a sudden stop is 
not desired. 

Brakes should be used only when a rather quick stop is to 
be made. When using the brakes the operator should apply 
pressure gradually; otherwise the wheels will be stopped before 
the forward movement of the car and this will result in excessive 
wear on the tires. 

When driving, the operator should keep his feet removed 
from the clutch and brake pedals, as otherwise undue wear will 
be thrown on the clutch and brake-operating mechanisms. Care 
must be taken also in automobiles equipped with self-starters not 
to push the starter pedal while the engine is running, as this would 
injure the starting gear. 

In timing the valves of an automobile engine it is necessary to 
set the camshaft of only one cylinder, as all the cylinders are 
driving from the same camshaft. The exact timing of the valves 
depends on the engine. For automobile motors, the exhaust 
valve ordinarily should open about 40° before the end of the power 
stroke, should remain open during the entire exhaust stroke, and 
should close about 10° after the beginning of the suction stroke. 
The inlet valve should open about the time the exhaust valve closes, 



AUTOMOBILES 163 

should remain open during the remainder of the suction stroke 
and close 30° to 40° after the beginning of the compression stroke. 

In cold weather all water from jackets and circulating system 
should be drained by opening all pet-cocks on cylinder jacket, 
pump, feed lines, and radiator. If it is not practical to drain the 
engine, some non-freezing jacket solution should be used. Glyc- 
erine, water and alcohol, or alcohol and water have been used 
successfully for non-freezing solutions. 

The more common automobile troubles and their remedies are 
illustrated in Table 6. 

An automobile engine will smoke if too much lubricating oil 
is used, if the lubricating oil is of poor quality, if the piston rings 
are worn or broken, or if the mixture of air and fuel is incorrect. 

Engine hissing may be produced by loose or broken spark 
plugs, by leaving relief or priming cocks open, by having exhaust 
pipe loosely connected, or by leaky gaskets or intake manifolds. 

Irregular action of the automobile engine may be due to 
incorrect fuel mixture, poor wiring such as defective insulation or 
defective connections, carbon deposits, poor fuel, or defects in 
carburetor, magnetos, spark plugs, or mechanism. 

Misfiring is often due to carbon deposits on the spark plug. 

Overheating of the engine may be due to incorrect valve or 
spark timing, defective water circulation, clogged radiator, or 
lack of proper lubrication. 

Engine knocks are due to rich mixture, too much spark 
advance, carbon deposits in the cylinder, loose or worn bearings, 
loose flywheel, or lack of lubrication. 

Gasoline Motor Cycles. — Motor cycles are propelled by air- 
cooled high-speed vertical gasoline engines. The motor-cycle 
engines operate usually on the four-stroke cycle and are built as 
single-cylinder, twin-cylinder, or four-cylinder types. The 
single- and twin-cylinder machines are most popular on account of 
the low first cost. The V twin cylinder is often used on account 
of its simplicity and lightness, there being only one crank and 
camshaft for both cylinders. 

The splash system of lubrication is commonly employed. The 
lubricating oil must be carefully selected, as the average tem- 
perature of the cylinder walls of the motor-cycle engine is 
higher than that of the water-cooled automobile engine. 



164 



FARM MOTORS 



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166 FARM MOTORS 

The jump-spark ignition system with magneto is employed. 
Float-feed carburetors of the automobile type are used. 

The speed of the engine is regulated by the spark and throttle 
control. Gear transmissions are used to a very limited extent. 

Belt, chain, and shaft drives are used. The coaster form of 
brake is used in some makes. 

Motor cycles are started by the pedal, by a hand crank, or by a 
foot lever. 

Some motor cycles are provided with a clutch to free the engine 
from the propelling mechanism and operate on two speeds. 

Problems: Chapter VI 

1. Compare the advantages and the disadvantages of the automobiles 
operated by gasoline engines, by electric motors, and by steam engines. 

2. Name the essential parts of a gasoline automobile. 

3. What are the advantages of a twelve-cylinder automobile engine as 
compared with a four-cylinder engine? 

4. Why are the cylinders of the majority of automobiles cast enbloc? 

5. Sketch and compare the tee-head, ell-head, and valve-in-the-head 
types of motors. 

6. Describe, using a clear sketch, the thermo-syphon system for cooling 
automobile motors, and compare this with the forced-circulation system. 

7. Explain the action of the sleeve-valve type of motor. 

8. Which type of valve is most commonly used in automobile motors? 

9. Sketch two types of clutches and explain how they work. 

10. Sketch and explain the progressive sliding-gear transmission system. 

11. Explain, with clear sketches, the selective sliding-gear transmission 
system. 

12. Using Fig. 137 in the book and models, if available, make several 
views of the planetary system of transmission and explain how this system 
works. 

13. Make a clear sketch and explain the friction drive. 

14. Compare the four systems of transmission as to advantages and dis- 
advantages. 

15. Sketch and describe some form of differential for automobiles. 

16. Show by means of sketches what is meant by a semi-floating and by a 
full-floating rear axle. * 

17. Explain by means of sketches the steering mechanism of an 
automobile. 

18. What are the functions of the accelerator, the hand levers on the steer- 
ing wheel, and the foot pedals of the automobile? 

19. What are the functions of the service brake and of the emergency 
brake? 



AUTOMOBILES 167 

20. Explain three gasoline feed systems for automobiles. 

21. What is the function of a master vibrator in an automobile ignition 
system ? 

22. Make a clear wiring diagram of the ignition systems for a four 
cylinder automobile engine, using batteries with a master vibrator and with 
four non-vibrating coils. 

23. Explain with clear sketches and diagrams the Atwater Kent ignition 
system. 

24. Give clear sketch showing the fundamental parts of the Delco igni- 
tion system. 

25. Compare the various systems used for automobile ignition. 

26. Which parts of an automobile require lubrication? 

27. WTiy should the lubrication of the steering wheel receive more care- 
ful attention than that of any other part of an automobile? 

28. What systems of lubrication are most commonly used for automobiles? 

29. What are the objections to a lubricating oil which is too heavy? to an 
oil which is too light? 

30. What are the resultsof using insufficient lubricating oil? Of using too 
much lubricating oil? 

31. Give directions for starting an automobile motor by hand-cranking. 

32. Explain, with clear sketches, the action of a two-unit electric starter. 

33. Give directions for starting, for reversing, for stopping, and for 
operating an automobile. 

34. Make a chart showing the most common automobile troubles and 
their remedies. 



CHAPTER VII 

TRACTION ENGINES 

Fundamental Parts of a Traction Engine. — A steam or a gas 
engine, explained in the previous chapters, can be converted 
into a traction engine by mounting it on trucks and providing 
additional mechanisms, so that the engine not only will be 
capable of producing rotation at a shaft, but also will move itself 
over fields and highways, thus performing the work of many 
horses in a cheaper, quicker and better manner. 

All traction engines must consist of the following fundamental 
parts : 

1. Power Plant. — This, in the case of steam traction engines, 
consists of a steam engine and boiler. Gas traction engines 
employ an internal-combustion engine burning gasoline, kerosene, 
or some heavier oil. 

Power-plant accessories include valves and piping from boiler 
to engine, fuel hopper, water tank, safety valve, water glass and 
try-cock, steam gage, blowoff, pump or injector or both, a stack 
and spark arrester. Some steam traction engines have also a 
feed-water heater which heats with exhaust steam the feed water 
before it enters the boiler. The accessories of the gas traction- 
engine power plant are fuel tanks, water tanks, batteries and 
battery boxes, magnetos, carburetors, cooling systems. 

2. Transmission Mechanism. — The speed of the engine is too 
great for direct utilization, and a train of gears must be inter- 
posed between the engine and drive wheels. 

3. Reversing Mechanism. — Reversing of a steam traction 
engine is accomplished either by a link similar to that used in 
locomotive practice, or by some form of single eccentric radial 
valve gear. It is more difficult to reverse a gas traction engine 
and a train of gears, similar to that of an automobile, must be 
employed. 

4. Steering Mechanism. 

168 



TRACTION ENGINES 169 

5. Differential or Compensating Gear. — The purpose of this is 
to allow one drive wheel to revolve independently of the other, 
this being necessary when turning corners, as is the case with 
automobiles (Chapter VI). 

6. Friction clutch for disengaging engine from propelling gear, 
so that the power of the engine can be utilized for the driving of 
separators or other machinery. 

7. Traction-engine frames for supporting the power plant, 
transmission mechanism and other parts and for. keeping all 
parts in proper alignment. Structural-steel I-beams, angles and 
channels are employed for frame construction. Cast iron is 
also used for certain parts. 

8. Traction or drive wheels (Figs. 161 and 162), which must 
be provided with lugs to give them a firm footing on the ground, 
and with mud shoes. 

9. Front Wheels. — These are made smaller and lighter than 
the traction wheels, and are provided with smooth tires. To 
prevent skidding the front wheels are built with a rim in the 
center (Fig. 170). The front wheels turn upon an axle which 
is attached to a ball and socket joint, or to some similar mechan- 
ism, so as to allow for uneven ground and also to facilitate 
steering. 

Steam Traction Engines 

Boilers. — The boiler of the steam traction engine is internally 
fired. Some builders utilize the return-flue type (Fig. 158), 
others the direct-flue or the locomotive type (Fig. 159). 

Coal, straw, wood and crude oil are used as fuels for traction 
engines. In some states lignite is used. Some builders supply 
traction engines with attachments for converting them from coal- 
burners into oil-burners. 

When using straw for fuel, the furnace is modified as shown in 
Fig. 160. Slab grates are then substituted for the ordinary coal 
grates and the straw is fed through a chute S. A hinged trap 
T is provided to prevent the entrance of air when the straw is 
not being fed. 

To maintain the proper draft, steam traction engines are pro- 
vided with a blower through which live steam is passed into the 



170 



FARM MOTORS 



smoke stack when starting. When the engine is running it 
exhausts into the stack through an exhaust nozzle. 

In some makes of traction engines, the boiler is mounted upon 
the truck and is used as the foundation for the engine (Fig. 161). 




Fig. 158. — Flue-type boiler. 




Rear Draft Opening 



Firebox 

rut 

"Wafer leg 
"Waste Sheet 
"front Draft Opening 



Fig. 159. — Locomotive-type boiler. 

Other types (Fig. 162) have the engine mounted under the boiler, 
the frame supporting both engirfe and boiler. 

Pumps. — Three types of feed pumps are used on steam trac- 
tion engines : the independent pump which is similar to the types 
illustrated in Chapter III, the crosshead pump P (Fig. 163), 



TRACTION ENGINES 



171 



which is driven from the engine crosshead C, and the gear-driven 
pump (Fig. 164). As in the case of stationary engines, two inde- 
pendent methods should be provided for feeding water into a 
traction engine boiler, using either two pumps or an injector and 
a pump. 

Feed-water Heaters. — Feed-water heaters are used on some 
traction engines. The type often employed is illustrated in 
Fig. 165. The feed water passes around the tubes and the 
exhaust steam passes through the tubes. 

Engine Types. — The type of engine usually employed is some 
simple form of steam engine with a slide valve (Fig. 166). Some 




Fig. 160. — Furnace for straw fuel. 

traction engines have double-cylinder engines. Compound 
engines (Fig. 167) are also used to some extent. 

The details of the engines, governors and accessories do not 
differ from those described in Chapter IV. 

Reversing Mechanisms for Steam Traction Engines.— A steam 
traction engine can be reversed either by a Stephenson link 
similar to that used on locomotives, or by some form of single- 
eccentric radial valve gear. 

To reverse an engine by means of the Stephenson link, it 
must be provided with two eccentrics, each being connected by 



172 



FARM MOTORS 




TRACTION ENGINES 



173 



an eccentric rod to the end of a link. A block connected to the 
valve slides along a groove in the link. 







• l*"^fe^ ' 1 X 'X*' - , ,- ; ■ .«4 




>^^^i^^^^^^^S\^ 





Fig. 162. — Undermounted traction engine. 




Fig. 163. — Cross-head pump. 
PumpDrive 



J-"' Gear Air Chamber i_ 1 li Cap for Valve Chamber 

«, -Pump Crank Shaft fUmpHeAWP^P9 e ^^¥ 



/Pump Conn. Rod ^^^U^"^ 

Jllllllllii,.... 

Yoke-' 



'•-Pump Drive Pinion ump 0/ \=f==^ ] - 5 
Png.CrankShB-' ® QuadrantShe/f- 

Fig. 164. — Gear-driven pump. 

This type of reversing link as applied to a traction engine is 
illustrated in Fig. 168. The two eccentrics shown at E are 



174 



FARM MOTORS 



attached to the curved link L by means of the eccentric rods A 
and B. The position of the link is varied by the reverse lever 
through the reach rod. In one position of the link the motion 
to the valve is given by one eccentric, driving the shaft in one 
direction. This direction of rotation is reversed by raising the 




Feed-water heater. 



link, so that the valve receives motion from the other eccentric. 
If the reverse lever is moved so that the block is in the middle 
of the link, the motion given by both eccentrics will be equal and 
opposite, and the valve will have no motion. 




Fig. 166. — Engine for traction engines. 

Most traction engines employ a single-eccentric radial valve 
gear (Fig. 169). This reversing gear consists of an eccentric 
fastened on the crankshaft with an eccentric strap which has an 
extended arm, pivoted in a sliding block. The block slides up and 



TRACTION ENGINES 



175 



down in a guide and gives motion to the eccentric rod, which is 
transmitted to the valve through the rocker arm and valve stem. 
The block guide is hung on a trunnion and it can be tilted in any 
direction by the reverse lever acting through the reach rod. The 



LiveSteam-: Steam 'Chest Cover 



"mmifisr 




■ Cylinder Head 



Fig. 167. — Compound engine for traction engines. 



angle at which the guide is set determines the direction in which 
the engine is to run. The reverse quadrant is usually provided 
with three notches. When the reverse lever is in the central 



*S »• mam 
SB 


s-A A 




^ '^j 



Fig. 168. — Stephenson reversing link. 

notch, no motion is given by the sliding block to the valve stem. 
In the position shown, the block sliding up and down in the block 
guide moves the valve in one direction. Placing the reverse 
lever in the notch at the extreme right reverses the engine. 



M 



176 



FARM MOTORS 



Steering. — Steering is accomplished by turning the front axle. 
This is done by chains C (Fig. 170) which wind upon a spool. 
The spool is operated by hand through a worm W and pinion P 
(Fig. 170). Another method is to operate a screw by the worm 



Sliding Black- 
Eccentric 
Strap 
Reverse 
Reach 
Rod- 

Eccentric 



Rocker Exhaust Port 
Arm 




Fig. 169. — Radial valve gear. 

and pinion, the screw moving a nut which is connected by a 
system of levers to the front axle. Some traction engines em- 
ploy steering mechanisms similar to those of automobiles (Chap- 



^^^1: in| 

Tl 

V * ' .— fa— 7 — ** 




■.-■.£■ I '^ ■.tf 


J3W* 


aV'^lJI 




: r-V 





Fig. 170. — Traction engine illustrating steering mechanism. 

ter VI). In large traction engines steering is accomplished by 
power furnished by the engine through a friction disc. 

Transmission Systems and Differentials. — A friction clutch, 
the function of which is to disengage the engine from the pro- 



TRACTION ENGINES 



177 



pelting gear, is illustrated in Fig. 171. The flywheel W is fixed 
to the engine shaft, and, when used as a belt wheel, it is not con- 
nected to the arm C, and thus does not transmit motion to the 
pinion F which is rigidly connected with the arms C. When the 
clutch is thrown in, pressure is applied at E which rests in a groove 
in the piece D. This results in B crowding the shoe A against 
the inner rim of the flywheel. The friction clutch has two shoes 
made of wood or of some other yielding material A A, which press 
against the inner rim of the flywheel when the clutch is thrown 




Fig. 171.— Clutch. 



in, and this transmits the motion of the engine through the arms 
C and pinion F to the transmission. Means are provided for 
taking up the wear on the shoes so as to keep the clutch effective 
at all times. 

The transmission mechanism delivers the power from the 
engine to the traction wheels which must revolve slower than the 
engine crankshaft. The transmission system of a steam traction 
engine is very simple and consists of a train of spur gears (Fig. 
172). The gear A receives motion from the engine and delivers 
this through the train of gears to the gear B, which is connected 
to the traction wheel. 

When a traction engine turns a corner, the drive wheel on the 

12 



178 



FARM MOTORS 



outside of the curve must turn faster than that on the inside. If 
the two drive wheels were rigidly connected, one would have to 




Fig. 172. — Traction-engine gearing. 





Fig. 173.— Differential. 

skid or slip, when turning a corner, and this would throw a great 
strain on the front wheels and axles. The differential, sometimes 



_: 



TRACTION ENGINES 



179 



called a compensating gear, allows, if occasion demands, one 
drive wheel to move faster than the other. 

In principle the traction-engine differential is similar to the 
automobile differentials (Figs. 141 and 142). 

The differential can be placed between the two drive wheels 
on the rear axle. A more common method is to have the 
differential on a separate shaft, the traction wheels being driven 
from that shaft by means of pinions. 



P 






Li 




H 









Fig. 174.— Differential. 



The principle of differentials as applied to steam and gas 
traction engines is illustrated in Figs. 173 and 174. The differ- 
ential shaft S consists of two parts, each being connected either 
directly or through gears to the drive wheels. Two bevel 
gears are keyed to these two differential shafts and engage 
several bevel pinions, marked B, which turn freely on their 
respective shafts. The power from the engine is transmitted 
through the pinion P to the large spur gear A . When the engine 
is going ahead on a level road and both drive wheels are rotating 
at the same speed, the two bevel gears will also revolve at the 
same speed and the small pinions marked B will remain station- 
ary. In turning a corner or in meeting some obstruction, if the 



180 



FARM MOTORS 



drive wheel connected to one bevel gear moves slower than that 
connected to the other, D, the pinions B will revolve on the bevel 
gear D. In other words, the difference in motion between the 
two drive wheels is compensated for by the revolution of the 
pinions B. 

Another traction-engine differential, as applied to gas traction 
engines, is shown in Fig. 175, the letters designating the same 
parts as in Figs. 173 and 174. The two pinions E and F connect 
the differential with the two drive wheels. W is a brake wheel. 




Fig. 175. — Gas traction-engine differential. 



Gas Traction Engines 

The term "gas traction engines" is applied to such as are 
propelled by internal-combustion engines. The fuels most com- 
monly used are gasoline, kerosene and the heavier oils. 

The use of gas traction engines has been increasing much more 
rapidly than that of steam traction engines. The reasons for this 
are as follows: 

1. The gas traction engine is made in many special designs 
suitable for various uses. 

2. The steam traction engine is practical only in large powers, 
while gas traction engines are built in sizes capable of pulling as 
few as two plows and as many as fourteen plows. This also 
means that gas traction engines sell at sufficiently low cost to 



TRACTION ENGINES 



181 



enable the fairly small farmer to use this form of mechanical 
power. The prices of gas traction engines vary from $500 to 
$4,500. 




Fig. 176.— Single-cylinder motor. 




Fig. 177. — Twin-cylinder two-stroke cycle motor. 



3. The operator of the steam traction engine must carry a tank 
wagon with water and a bulky fuel supply. This necessarily 



182 



FARM MOTORS 



limits the amount of plowing by this form of engine. With the 
gas traction engine the fuel and water supply occupy little space. 

4. Considerable time must be consumed in getting up steam 
for operating a steam traction engine. 

The Gas Traction-engine Motor. — The majority of gas 
traction engines employ internal-combustion motors which 
operate on the four-stroke Otto gas-engine cycle. The motors are 
either vertical or horizontal and of the long-stroke type and oper- 
ate at moderate speeds as compared with automobiles. 

The vertical motor resembles the automobile motor, but is 
usually heavier. The cylinders of the vertical motor are cast 




Fig. 178. — Two-cylinder opposed motor. 



singly (Fig. 122) ; some makers cast cylinders in pairs. The four- 
cylinder en-bloc type, common in automobile practice, is used 
to a limited extent for traction engines. 

The horizontal motor is more difficult to lubricate and is bound 
to wear more rapidly than the vertical types. 

The types of motors used are single-cylinder (Fig. 176), twin- 
cylinder (Fig. 177), two-cylinder opposed (Fig. 178), and four- 
cylinder (Fig. 179). 

The single-cylinder motor (Fig. 176) is usually of the long- 
stroke heavy-duty horizontal type and has a heavy flywheel. 

The two-cylinder traction engine is built as a twin-cylinder 



TRACTION ENGINES 



183 



motor with cylinders mounted side by side, at one side of the 
crankshaft (Fig. 177), or as a two-cylinder opposed motor (Fig. 
178) with two cylinders set horizontally on the opposite sides of 
the crankshaft. The two-cylinder opposed motor is better bal- 
anced and can be operated with lighter flywheels. The twin- 
cylinder type of motor (Fig. 177) occupies less space and has bet- 
ter carburetion. 

Multiple-cylinder motors are more commonly used, as they 
are lighter than the single-cylinder motor for the same power 




Fig. 179. — Four-cylinder traction-engine motor. 

developed. Increasing the number of cylinders produces also a 
motor which has a more uniform turning effort at the crankshaft, 
the power impulses taking place more frequently. 

The four-cylinder vertical motor (Fig. 179) is the most common 
type for large traction engines. The cylinders of the four-cylinder 
motor are usually placed so that the crankshaft is parallel to the 
tractor frame. In some designs the motor is set crosswise of the 
frame. In the crosswise arrangement the motor drive is direct, 
in the other method, the drive to the transmission is through 



184 



FARM MOTORS 



bevel gears. While the direct drive eliminates the use of a 
bevel gear, the other design can be built with longer bearings 
without widening the frame. The length of the bearing is ah 
important consideration in large traction engines. 

The motor crankshaft has two, three, or five main bearings and 
one camshaft usually operates all the valves. The valve cam- 
shaft is driven from the motor crankshaft by a two-to-one gear, 
as is the case in stationary and automobile engines. 



1 


— ■ 

Mm -'§&■ il 


[■ 


" x -^ ■ / U N 1 1 \_1 




9Kk ^^^^^~^^^^3^U» ™^ j — a -^* ; * ■- ' hm^^^^m^bi^^hI 



Fig. 180. — Traction-engine cooling system. 



Traction-engine cylinders are made of cast iron and are 
provided with jackets for liquid-cooling. Air-cooled motors are 
not practical for traction engines. 

Water is usually used as the cooling medium. Heavy oils and 
the various anti-freezing compounds, such as glycerine, alcohol 
and water, or alcohol and water, are also used to some extent. 

A forced system of water circulation is usually employed with a 
rotary, a centrifugal, or a plunger pump. In the rotary pump the 
water is circulated by revolving gears and in the centrifugal 
pump by an impeller or paddle wheel. The rotary or centrifugal 
pumps are more generally used, as they are more simple. The 



TRACTION ENGINES 185 

thermo-syphon system of water circulation (Fig. 125) is used in 
some makes of traction engines. 

Some form of radiator (Figs. 180, 181) is employed which acts 
as a water tank and cooler. In most traction engines the radia- 
tors are similar to those of automobiles but heavier; a cooling fan 
is used to circulate the air through the radiator. The exhaust 
gases are also utilized in some designs to aid in the circulation of 
the air. 

The poppet type of valve (Fig. 127) is always employed. 
Valves are constructed of a nickel-steel or cast-iron head, and 
a carbon-steel stem, stem and head being welded together. 

The valves are arranged, as in automobiles (Figs. 130, 131, 
132), in three distinct ways: namely, the tee-head, the ell-head 
and the valve-in-the-head construction. With the tee-head or 




Fig. 181. — A small gas traction engine. 

the ell-head construction the valve seats are in a pocket cast on 
the side of the cylinder proper, which forms a very inefficient 
combustion space. The valve-in-the-head motor has a very 
compact combustion chamber. 

In the valve-in-the-head type of motor, the cylinder head 
carrying the valves is a separate casting (Fig. 182) or has the 
valves mounted in removable cages (Fig. 183). 

Many makes of traction-engine cylinders are built with remov- 
able heads (Fig. 182). When the cylinder head is a separate 
casting, it can be removed easily for the purpose of cleaning, and 
the valves, with this form of construction, can be more thoroughly 
water-jacketed than when mounted in cages. 

When the valves are placed in cages (Fig. 183), the cage con- 
tains a seat for the valve and a guide for the valve stem. 



186 



FARM MOTORS 




Fig. 182. — Traction-engine cylinders with removable heads. 




AIR 
PASSAGE 



Fig. 183. — Valves in cages. 



TRACTION ENGINES 



187 



The exhaust valve seat is usually water-jacketed and in some 
designs the inlet valve seat is also water-jacketed in order to keep 
down the temperature of the incoming mixture. 

Traction engines are generally constructed with mechanically 
operated inlet and exhaust valves. 

Some gas traction engines are provided with an auxiliary ex- 
haust port. With this construction the exhaust gases pass 
directly into the exhaust pipe, removing the hottest gases from 
the exhaust valve and decreasing the pressure at the time the 




Fig. 184. — Throttling governor. 



exhaust valve opens. This feature is particularly advantageous 
when the engine is operated continuously at heavy loads. 

Traction engines are governed by the hit-and-miss or by the 
throttling type of governor. The hit-and-miss governor is not 
adapted for work where close regulation is essential. The major- 
ity of modern gas traction engines are equipped with throttling 
governors. The throttling governor is of the centrifugal type 
and controls the carburetor throttle (Fig. 184). In some cases 
the controlling mechanism is arranged so that the governor may 



188 



FARM MOTORS 



be cut out, and the carbureter throttle is controlled by a hand 
lever. 

The speed of various makes of traction-engine motors varies 
from 365 to 1,500 r.p.m. The majority of motors operate at 
speeds of 500 to 750 r.p.m. 

The belt horsepower of various makes of motors varies from 
10 to 120 h.p. 




Balanced 
Valve 



Valve Chamber 



Admission Manifold^ 
to Cylinders 



Fig. 185. — Traction-engine carburetor and governor. 



Carburetors for Traction Engines. — Float-feed carburetors of 
the single-jet automobile type illustrated in Chapter V are used. 
The simpler designs, such as the Kingston (Fig. 78), are generally 
employed. 

The arrangement of carburetor and throttling governor for 
one form of traction engine is illustrated in Fig. 185. The car- 
buretor is of the concentric-float type. The gasoline passes 
through a strainer before entering the float chamber. The 



TRACTION ENGINES 



189 



fuel mixture on the way to the engine cylinder must pass through 
a balanced throttle valve which is under the control of the 
governor. 

To burn kerosene, some makes employ the ordinary float-feed 
carburetor, which has a jacketed float chamberthrough which 




Fig. 186. — Kerosene carburetor. 



hot water passes. The kerosene carburetor illustrated in Fig. 
82 is used by some manufacturers. 

Another form of kerosene carburetor, called the Secor-Higgins, 
is illustrated in Fig. 186. The three compartments from right 
to left are for gasoline, water and kerosene. The lower section 
is the mixing chamber. Gasoline is forced into the mixing 



190 



FARM MOTORS 



chamber by means of a hand pump. Plunger pumps force 
water and kerosene into the compartments. The air enters 
through air intake ports. The amount of air entering the mixing 
chamber is controlled by the governor. The throttle opening 
which admits the mixture to the cylinder is also under the con- 
trol of the governor. 

With kerosene fuel, water is generally mixed with the air and 
fuel to prevent preignition. Very little water should be used at 
light loads, and the quantity of water injected at higher loads 




Fig. 187. — Wiring diagram for four-cylinder motor. 

should be sufficient only to produce proper operating conditions. 
With heavier liquid fuels, the capacity of an engine of the same 
bore, stroke and speed is increased by water injection. Water 
injection also reduces the amount of carbon deposit, but produces 
a slower burning mixture with the consequent poorer fuel 
economy. 

The majority of traction engines are equipped to burn kero- 
sene as well as gasoline. 

Ignition for Gas Traction Engines. — Nearly all traction engines 
operate with the jump-spark system of ignition (Chapters V and 
VI). The jump-spark system is more simple mechanically, 



TRACTION ENGINES 



191 



having fewer parts than the make-and-break system. The ig- 
nition system differs from that used in automobiles in that 
magnetos are commonly employed. In some cases the dual 
system is employed, in which the motors are started with current 
supplied from a dry or storage battery, but operate with mag- 
netos. In other makes, the motor is started on the magneto. 
The present tendency seems to be to eliminate the battery and 
to use the magneto for starting. 

A wiring diagram for a four-cylinder traction engine is illus- 
trated in Fig. 187. 

The make-and-break system of ignition is used to a limited 
extent for small traction engines in connection with a slow-speed 




Fig. 188.— Clutch. 



single-cylinder motor. With the make-and-break system an 
oscillating magneto (Fig. 100) is often employed. 

Transmission Systems and Differentials. — The clutch of the 
gas traction engine has the same function as that of the auto- 
mobile and connects or disconnects the motor from the propelling 
gear. The types of clutches used for gas traction engines are 
similar in principle to those illustrated in Figs. 133, 134 and 
171. The expanding-cone, expanding-shoe, multiple-disc, float- 
ing-plate and clamp-plate types are employed. Usually one part 
of the clutch is part of the flywheel. A traction-engine clutch is 
illustrated in Fig. 188. 

Some traction engines are constructed with a single reversing 



192 



FARM MOTORS 



mechanism and without speed- change gears, while other trac- 
tion engines have the reversing mechanism incorporated with 
the speed-change gears; some manufacturers employ a reversing 
mechanism which is separate from the speed-changing mechan- 
ism. The highest speed in the case of traction engines is usually 
obtained through gearing instead of by the direct motor drive. 
The reason for this is that the traction engine is used most of the 
time for plowing or for other heavy work, which requires a slow 
speed; by Operating the direct drive at the slower speeds the 
heavy work can be accomplished with few gears, thus increasing 
the efficiency of the drive. 




Fig. 189. — Traction-engine transmission system. 

One simple form of gas traction-engine gearing is illustrated 
in Fig. 189. The differential gear used in connection with the 
engine of Fig. 189 is of the spur-gear type similar in principle to 
that illustrated in Fig. 142. 

Another simple traction-engine transmission system is illus- 
trated in Fig. 190. 

A two-speed transmission system is shown in Fig. 191. The 
reversing mechanism consists of two bevel pinions (A, B) which 
are driven from the motor shaft. The bevel gears A and B 



TRACTION ENGINES 



193 



drive the differential driving gear D through the large bevel gear 
M. In the neutral position these bevel gears A and B revolve 




Traction-engine transmission. 




Fig. 191. — Two-speed transmission system. 



freely. The lever R is used for connecting either bevel gear A 
or B with the driving shaft. The lever S controls the speed- 



13 



194 



FARM MOTORS 



changing gears and the lever C is for the clutch. The shaft P 
is for the belt pulley. 

In some traction engines the speed-changing mechanism is 
similar to that used in automobiles. The type generally used 
is the selective-transmission system (Fig. 192). 

A friction drive (Fig. 193) is employed in some makes, this 
drive differing from the automobile friction drive in that the 
fibrous-covered friction wheel is mounted on the engine crank- 
shaft; in automobiles the disc is the driving member. 

In some designs clutches are used for reversing. A single 
lever operates two clutches, one of which is used for reversing. 




Fig. 192. — Selective transmission system. 



Differentials for gas traction engines were illustrated and de- 
scribed in connection with Figs. 173, 174, and 175. Spur-gear 
differentials similar to that of 142 are also employed in some gas 
traction engines. Some of the light traction engines dispense 
entirely with the differential and use only one traction wheel. 

Type of Traction. — The majority of traction engines use the 
two rear wheels as the traction wheels or drive wheels, while the 
two front wheels are for steering. Some makes use a traction 
drum, several are constructed so that the front wheels are the 
driving wheels, and in other makes, all four wheels drive. In 
the case of three- wheeled traction engines, one large drum, two 
front wheels, or two rear wheels are used for driving. 

Traction engines are also built on the "creeping-grip" or 
"caterpillar" principle (Figs. 194, 195, 196), which employ a 



TRACTION ENGINES 



195 



crawler instead of a wheel or drum. The object of this construc- 
tion is to have the traction wheels travel over a continuous, 
metalic track approximating as nearly as possible that over which 




Fig. 193. — Traction engine with friction drive. 



the locomotive travels. The creepers or tractor shoes run in- 
side a continuous belt. Power from the motor is transmitted 
from a jackshaft to the creeper drive wheels by a chain and 
sprocket drive on either side. The advantages of this construe- 



196 



FARM MOTORS 



tion are greater gripping surface for the same weight and better 
distribution of weight. 



^*%^ 








1 £ 






: ::l»;-: : -.y£r .:. C = 


'A\ 




7 


_ |-— ^ 


""lii 




mM^raEiS#JM^T~^|i 








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if' ' V' W ^ : 










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jsgfli 


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Fig. 194. — Creeping-grip tractor. 







jplt' 


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.j-pg^k; ''MBSmCSm, 


£_. ^* ft x «/„» - 





Fig. 195. — Caterpillar tractor. 

Uses of Traction Engines. — Desire on the part of farmers to 
raise large crops and to put under cultivation great areas of land 
created a demand for mechanical power. With mechanical power 



TRACTION ENGINES 



197 



the number of horsepower under the control of one man be- 
comes unlimited,. if the man controlling the mechanical power is 
willing to learn the simple fundamental processes which govern 




Fig. 196. — Track of crawler type tractor. 

the conversion of fuel into mechanical energy as well as the 
simple laws of mechanics which enable one to keep machines 
and mechanisms in adjustment and in perfect working order. 
A traction engine is capable of doing the following field work: 




Fig. 197. — Plowing, seeding and harrowing. 

Clearing the land : tearing out hedges, pulling up trees, stumps 
and stones. 

Preparing the seed bed and seeding with the operation of 
plowing, listing, disking, harrowing, drilling, seeding. 



198 



FARM MOTORS 







Fig. 198. — Deep plowing. 




Fig. 199. — Harvesting with steam traction engine. 



TRACTION ENGINES 



199 



Harvesting operations such as mowing, hay loading, hay hoist- 
ing, and drawing binders and diggers. 



- 


•J&mL* '"^Steffi 


ffofifef^ ■" 




■ "** rirBTirni 






• 

fe- i* , -v — • . ^.^'■**£MBBiaj 


... 


« ...'-' 


.."•--** <?.■'■'? s 



Fig. 200. — Harvesting with gas traction engine. 

With a traction engine the processes of plowing, seeding, and 
harrowing can be carried on in one operation (Fig. 197). Deeper 
and more uniform plowing (Fig. 198) can be carried on. Harvest- 




Fig. 201. — Tractor cultivator. 

ing operations with steam and gas traction engines are illustrated 
in Figs. 199 and 200. 

Some designs of traction engines are built low and are suitable 
for orchard cultivation. 



200 FARM MOTORS 

Power cultivators are being placed on the market which are 
suitable for cultivating corn and other rowed crops. One form 
of tractor cultivator is illustrated in Fig. 201. The motor of 
this machine is placed on the frame near the front and is a four- 
cylinder vertical internal-combustion motor with the cylinders 
cast enbloc similar to automobiles. One of the special features 
of this traction engine is that the two drive wheels are operated 
separately by means of friction-drive transmission. The mechan- 
ism is so arranged that one wheel can be held stationary while the 
other travels forward or backward. To facilitate turning around 
at the end of a row of corn, in order to go up in the next row, the 
operator throws out the gear connection in the steering apparatus 




Fig. 202. — Hay-bailing machine driven by traction engine. 

and the front wheel acts as a caster. Then, by operating the 
rear wheels, the machine can be made to turn completely around. 
The cultivator gangs are operated by the driver's feet. 

The traction engine is suitable for heavy-belt work, such as 
hay baling (Fig. 202), corn shelling, pumping water for irrigation 
and for other purposes, grinding feed, ensilage cutting, sawing 
wood, threshing, husking, hulling, shredding, filling silos, crush- 
ing rock, and elevating corn and grain. 

Traction engines can be used for hauling grain and other 
farm products to the shipping point or to the market; for haul- 
ing fertilizer and other material to the farm; also for moving 
houses, barns and other structures. 

In connection with road work, traction engines are used for 



TRACTION ENGINES 



201 



pulling graders (Fig. 203), scrapers, road plows, drags, and other 
road implements, as well as road materials. 

Traction engines can be used for digging irrigation ditches and 
for filling drainage ditches. 

Development of the Gas Traction Engine.— The development 
of the gas traction engine has been exactly the reverse of the 
automobile. The earlier automobiles were small and light in 
weight; the early gas traction engines were very heavy, develop- 
ing 60 to 100 hp. on the belt. At the present time traction 
engines developing 5 to 15 hp. on the drawbar (10 to 30 b. hp.),' 
and capable of pulling three or four 14-in. plows, are used in 



.111 j&j i . 


- ' ' ■• -"*5 "if 


-JJttSt, S*5wWfiBiMftw5'Et. -3T*^i' ■*.. : J fB fiPw ^ •'*>(*•'. ^WS^Jh^f?! *^ 


, 




Fig. 203.— Tractor used for pulling graders. 

great numbers in the corn belt. Large steam or gas traction 
engines developing 40 to 60 drawbar horsepower and capable 
of handling 10 to 14 plows, are used in the Northwest and in 
other parts where large areas must be cultivated and farm labor 
is scarce. The tendency seems to be for the large farmers to 
invest in several machines, each designed for a special purpose, 
than to buy one all-purpose machine capable of performing all 
the work of the farm. 

Attachments are available for converting an automobile into 
a light traction engine, capable of pulling one or two plows. The 
rear wheels of the automobile are replaced with pinions which 



202 



FARM MOTORS 



mesh with gears on the traction wheels. The traction wheels 
revolve on a special axle at a speed which is one-eighth to one- 
tenth that of the automobile rear axle. 

The traction engine probably will not replace the horse for 
all purposes very soon, but will replace many horses, on large 
farms, and especially in connection with the heavy farm work. 
The traction engine is a concentrated form of power plant which 
can work day and night, is not affected by heat, and can be used 
to advantage a large portion of the year. 

Economy of Gas Traction Engines. — The cost of operating a 
gas tractor depends upon many varying factors, such as the kind 
of fuel used, the cost of fuel, the cost of attendance, the character 
of the soil, and the type of machine. 

Experiments carried on during 1915-1916 in the engineering 
laboratories of the Kansas State Agricultural College indicate 
that the fuel consumption in pounds per brake horsepower per 
hour is very nearly the same for gasoline and for kerosene. The 
fuel consumption per brake horsepower per hour (average of 
tests on 12 different traction engines) was found as follows: 



Traction-engine rating in brake horsepower . . 
Gasoline consumption, pounds per horsepower 

Full load "... 

Half load 

Quarter load 



15 to 26 



0.855 
1.147 
1.853 



26 to 51 



0.720 
0.893 
1.416 



51 to 90 



0.73 
0.93 
1.47 



With kerosene at 10 cts. per gallon and gasoline at 20 cts. per 
gallon, the cost of gasoline fuel will be about twice that of kero- 
sene for the same power developed. The advantages of kero- 
sene fuel, due to the lower cost, are offset to a greater or less 
degree, depending upon the operator, by the added trouble in 
handling the traction engine. The life of the motor probably will 
be less with kerosene fuel. To this should be added the lower 
reliability insurance with the heavier fuels. In some work done 
by traction engines reliability is the most important factor. 

Rating of Traction Engines. — Two ratings are usually given 
to traction engines. One is in brake or belt horsepower. This 
means the actual power developed at the shaft of the engine, 



TRACTION ENGINES 203 

which can be utilized for driving various machines by means of 
a belt drive. 

The other rating is in tractive or drawbar horsepower. To 
obtain the tractive horsepower the amount of power lost in trans- 
mission to the drive wheels and that required to propel the trac- 
tion engine must be subtracted from the brake horsepower de- 
veloped at the shaft of the engine. 

The tractive horsepower depends on the kind of transmission 
gearing and on the character of the roads over which the traction 
engine must be propelled. It is equal to from one-half to two- 
thirds of the brake horsepower. As an illustration, a traction 
engine equipped with a 40-hp. engine will be able to produce only 
20 to 27 hp. at the drawbar under ordinary conditions. 

The belt horsepower of various makes varies from 10 to 120 
hp. and the drawbar horsepower from 5 to 60 hp. 

The ratings are usually expressed as 8-16, 5-10, or 40-80. 
These ratings mean 8 drawbar horsepower and 16 belt horse- 
power, 5 drawbar horsepower and 10 belt horsepower, etc. 

The relation between the rating and number of 14-in. plows 
a gas traction engine will pull is approximately as follows: 

Rating Number of plows 

5-10 1 or 2 

8-16 2 or 3 
10-20 3 

12-25 3 or 4 

20-40 5 or 6 

30-60 8 or 10 

Gas traction engines range in road speed from 1}^ to 10 miles 
per hour. The average road speeds are 2 to 3 miles per hour. 
The furrow speeds in miles per hour vary from 1 to 3J^. The 
average furrow speed is not greater than 2 miles per hour. 

The drawbar pull in pounds, of a traction engine, traveling 
at a rate of about 2 miles per hour, is approximately 180 times 
the drawbar horsepower. 

Operation and Care of Traction Engines. — The general direc- 
tions given regarding the care of stationary steam and oil en- 
gines apply also to the motors of steam and gas traction engines. 

The wearing surfaces must be well-lubricated or they will 
wear out, and lost motion in bearings must be avoided to prevent 



204 



FARM MOTORS 



pounding and broken crankshafts. Many of the traction-engine 
troubles can be traced to inefficient lubrication or to the use of 
poor lubricating oil. 

Bearings may be oiled by means of grease cups (Figs. 53, 54), 
or by sight-feed lubricators (Fig. 56). Gears are lubricated with 
grease or with some other heavy lubricant. Transmission grease 
is generally used for the transmission. In some cases heavy 
steam-cylinder oil is employed for the same purpose. Cylinders 
for steam traction engines are lubricated with heavy steam- 
cylinder oil by a mechanically driven oil pump or by an automatic 
sight-feed steam lubricator (Fig. 57). A medium gas-engine 
cylinder oil should be used for lubricating gas traction-engine 




,-'Cup Grease 



Fig. 204. — Traction-engine lubrication chart. 



cylinders. A lighter gas-engine cylinder oil should be used in 
cold than in warm weather. 

A combination of splash and forced-feed oiling system is often 
used for traction-engine lubrication. 

The instructions furnished by the manufacturer regarding 
the kind of oil to be used and the lubrication of the various parts 
should be carefully followed. A lubrication chart for one make 
of traction engine is illustrated in Fig. 204. The bearings of 
magnetos require frequent attention. A high-grade sewing 
machine oil should be used for this purpose. 
. All reputable manufacturers test their traction engines before 
shipment from the factory. The purchaser, upon receiving a 
traction engine, should carefully examine all parts. The rail- 



TRACTION ENGINES 205 

road company and the manufacturers should be notified at once 
if any parts are damaged or missing. 

Before attempting to start the engine, it should be gone over 
carefully, all nuts tightened, bearings properly set, lubricators' 
filled, and clutch adjusted so that all shoes come into contact 
with the inside of the wheel at the same time. The operator 
should make certain that the engine has a sufficient supply of 
fuel and water and that the lubrication system is in good working 
order. The fuel for a gas traction engine should be strained. A 
chamois skin strainer is best for gasoline while a funnel with a 
fine screen will be satisfactory for kerosene fuel. A strainer will 
prevent dirt from getting into the carburetor and the supply 
pipes from clogging. 

In the case of steam traction engines the boiler is filled about 
two-thirds full of water and the fires are started as explained in 
Chapter III. Upon first using a boiler it is liable to foam, espe- 
cially if the water is bad, but after washing the boiler, or changing 
the water several times, the oil and grease on the boiler plates 
are removed. Clear, soft water should be used. Care should be 
taken not to use water which contains lime. The water gage 
cocks should be tried often and the water level should not be 
allowed to be below the second gage. Before the feed-water 
pump is started the operator should make certain that the feed 
line to the boiler is not closed. It is desirable to use the pump 
and to keep the injector as a reserve for emergencies. In 
simple single-cylinder traction engines the safety valve is set at 
about 130 lb., in compound engines at 160 lb. The fire should 
be kept thin. The operator should fire frequently and lightly. 
In operating a steam traction engine on the road care must be 
taken not to allow the engine to remain with its rear end elevated 
for any great length of time, as this may result in the overheating 
of the crown sheet. The water glass must be blown out two or 
three times each day and the safety valve should be kept in good 
working order. The reverse lever should be kept as close to the 
center notch of the quadrant as possible in order that the engine 
may operate at its best economy. When running, the throttle 
should be wide open and the steam supply to the engine should 
be varied entirely by the reverse lever. The fire flues of the boiler 



206 FARM MOTORS 

should be cleaned frequently, as the cleaner the flues the less fuel 
will be required to keep up steam. 

In starting a gas traction engine, the operator should be cer- 
tain that the change gears are in the neutral position and that the 
clutch is disengaged. In the case of a dual-ignition system the 
switch should be closed on the battery side. The spark lever 
is then retarded and the carburetor throttle is opened so as to 
admit a small supply of fuel. The shutoff valve at the gasoline 
tank is opened, the cylinders are primed through the priming 
cocks, and the motor is cranked. The quicker the crank is turned 
the easier the engine will start. After the motor starts, the 
spark lever is advanced. Some traction engines are started by 
means of small auxiliary gasoline engines. 

To put the traction engine in motion the clutch is thrown in 
gradually after the lever controlling the change gears has been 
shifted to the position required. In stopping a traction engine, 
the carburetor throttle is closed, the switch is opened, the clutch 
is disengaged and the change-speed lever is placed in neutral. 
Failure to place the lever controlling the change gears in the 
neutral position will start the tractor if the clutch is disengaged. 
The operator never should try to reverse a traction engine without 
first bringing the machine to a stop. The operation of the trac- 
tion engine is controlled by the carburetor throttle lever. 

One accustomed to driving an automobile will find the trac- 
tion-engine steering mechanism less sensitive. More turns of 
the steering wheel will be necessary on account of the slower speed 
of the traction-engine motor and the lower gear ratio of the 
steering gear. 

In running a traction engine on the road, the operator should 
keep his eyes on the front wheels to prevent accidents. In case 
a traction engine is landed in a hole, it can be pulled out by 
placing chains, boards, or straw under the drive wheels. The 
same advice applies when the engine slips. Before crossing a 
bridge the operator should ascertain that it is safe. In case of 
doubt, planks should be placed to distribute the load. 

A competent operator handles a traction engine slowly and 
deliberately, and never hesitates to stop, if something goes 
wrong with any part of the engine. 

Overloading a traction engine is a serious mistake. 



TRACTION ENGINES 207 

A traction engine should be kept at all times in adjustment and 
in perfect working condition. This cannot be accomplished un- 
less the engine is housed properly. A traction engine represents 
a large investment, the depreciation of which can be greatly re- 
duced if the housing question is carefully considered. A frame 
or a concrete structure should be provided which not only will 
house the traction engine but will leave sufficient space for a 
farm workshop where ordinary repairs can be made. 

The tractor operator should do his repairing systematically. 
At the completion of a hard season's work the machine should be 
thoroughly overhauled. All old grease and oil should be removed 
from cylinders, bearings and transmission case. All parts should 
be cleaned with kerosene. Bearings should be examined, and ad- 
justed by means of liners. In ordering repairs for engines, give 
description or sketch of the part as well as the number and letters 
found on the parts wanted. The number and size of the engine 
also should be stated. 

The clutch should be examined frequently for worn parts. 

It is well to have on hand an extra clutch lining, a set of piston 
rings, an extra connecting rod, several new spark plugs, cotter 
pins, belts, and nuts of various sizes and such other small repair 
parts as may be worn out or lost in the operation of the engine. 

Valves for gas traction engines should seat properly and should 
be reground if indications show wear. To grind the valve into 
its seat the valve spring is removed and the valve is taken out. 
Flour emery dust and oil, or fine carborundum valve-grinding 
paste and oil is placed on the valve seat. By using a brace 
holding a screw- driver bit in the slot on the top of the valve, the 
valve may be revolved back and forth on the seat with very 
little effort. It is best to place a light spring on the valve stem 
so that the valve is held up and off from its seat. 

The time of opening and of closing of the valves of gas trac- 
tion engines depends upon the speed of the engine. The valves 
of a high-speed engine should open sooner and remain open longer 
than those of a slow-speed motor. Ordinarily, the exhaust 
valve should open 30° to 50° before the beginning of the exhaust 
stroke and should remain open 4° to 10° after the completion of 
that stroke. The inlet valve should open 5° to 12° after the 



208 



FARM MOTORS 



beginning of the suction stroke and should close 18° to 25° after 
the completion of the suction stroke. 

The common sources of trouble with a traction engine are 
due to the incompetency of operators, who are responsible for 
poor or insufficient lubrication, dirty fuel, carbon deposits, poor 
fuel economy and high depreciation. 

When it is desired to draw a number of machines at the same 
time by means of a traction engine, care must be taken that 
the machines are properly hitched to the engine. The hitch 
required for plowing is very simple. A hitch for three-disc 
harrows is illustrated in Fig. 205. This consists essentially of 
a supplementary drawbar B which is connected to the main 
drawbar by the chain A. 




Fig. 205. — Hitch for three-disk harrows. 



In laying by the engine for the winter, it should be placed under 
cover and be protected from rain and snow. It is well to remove 
pistons from the cylinders of gas traction engines, clean all 
deposits and then oil pistons, cylinders and valves with a heavy 
oil. Magnetos and batteries should always be removed to a dry 
place. All parts should be carefully drained. In fact, it is well 
to remove all drain cocks so as to prevent any water from remain- 
ing in cylinders and tanks. 

The success of a traction engine depends not only on the 
operator but also on the business ability of the owner. The 
farmer should so plan his work that the traction engine is used 
not only for plowing, but for many other kinds of work. To 
secure the best results the traction engine should be kept busy 
mostof the year. 



TRACTION ENGINES ■ 209 

Problems: Chapter VII 

1. Name the fundamental parts of a traction engine. 

2. What types of boilers are commonly used on steam traction engines. 
Sketch one type. 

3. Describe, using clear sketches, two types of pumps used for feeding 
water to steam traction-engine boilers. 

4. Sketch and explain in detail two types of reversing mechanisms for 
steam traction engines. 

6. In which respect does the steering mechanism for a traction engine 
differ from that for an automobile? 

6. Sketch and explain some form of differential for traction engines. 

7. Why does the steam turned into the stack of a steam traction engine 
improve the draft? Explain in detail. 

8. To which types of traction engines does the term "gas traction engine" 
refer? Give reasons for the great popularity of the gas traction engine. 

9. Explain the distinctive features of gas traction-engine motors and com- 
pare the traction-engine motor with automobile motors. 

10. Explain differences in construction between radiators employed for 
automobiles and for traction engines. 

11. Show by means of clear sketch the action of a throttling governor. 

12. Sketch and explain a jacketed float-feed carburetor, suitable for burn- 
ing kerosene. 

13. Explain with clear sketches, a kerosene carburetor suitable for traction 
engines. 

14. Give a wiring diagram for a four-cylinder traction engine. 

15. Explain, using clear sketches, two different types of transmission sys- 
tems suitable for traction engines. 

16. Investigate and report why some small traction engines are capable 
of working satisfactory without the use of a differential. 

17. Explain the various types of traction. 

18. What are the advantages of the gas traction engines which utilize a 
crawler instead of a wheel or drum? 

19. What type of field work and of belt work is a traction engine capable 
of doing? 

20. What are the fundamental parts of a power cultivator and in which 
respect does this differ from the ordinary traction engine? 

21. How does the cost compare of operating a traction engine with gasoline 
and with kerosene fuel. 

22. A farmer invests in a 10-20-hp. traction engine $1,000. If he uses 
the traction engine only 60 days per year, calculate the approximate cost of 
this form of power per year, taking into consideration interest on investment 
at 6 per cent., depreciation 10 per cent., taxes, insurance, repairs. Com- 
pute this upon the basis of the market price for gasoline and for kerosene 
respectively. 

23. What is the relation between the belt horsepower and the drawbar 
horsepower of a traction engine? 

14 



210 FARM MOTORS 

24. What is meant by the traction engine rating 5-10? 

25. What determines the number of plows that can be pulled by a trac- 
tion engine of a given rating? , 

26. What precautions must be taken in starting and in operating a gas 
traction engine? 

27. Explain in detail how to grind a gas-engine valve. 

28. Give directions for setting the valves of a gas traction engine. 

29. Report on the possibility of utilizing the ordinary automobile as a 
traction engine. What special attachments would be needed? 

30. What precautions must be observed in laying by a traction engine for 
the winter? 



;; CHAPTER VIII 

WATER MOTORS 

A water motor converts the energy possessed by moving or 
falling water into useful work. 

Determining the Power of Streams. — Before explaining the 
various commercial types of water motors, the method of deter- 
mining the power available in any water stream will be given. 

The power available in any stream depends on the head of 
water and on the quantity of water which can be utilized in a 
water motor. 

The term head is applied to the fall of water available. The 
head can be determined most readily by running an engineer's 
level from a point at the upper line of water flow to a point at 
the lower line of flow. The vertical distance between the two 
points gives the head of the stream. 

One method of determining the quantity of water available 
for utilization in a motor, is to find the cross-sectional area of 
the stream, and to multiply this by the velocity of the stream. 
The cross-sectional area of a stream can be obtained by multiply- 
ing the average depth of the stream by its width. To find the 
velocity, several floats are dropped into the water at a place where 
the depth and width is uniform for some distance, noting the 
number of seconds it takes for the floats to pass a certain dis- 
tance. Since the velocity of a stream is greatest at the center 
and is least at the bottom and sides, the velocity as obtained 
by floats should be multiplied by 0.80 to obtain the average 
velocity. 

As an illustration, the average width of a stream is 10 ft., 
its average depth is 4 ft., and the velocity of the water, as obtained 
by floats, is 30 ft. per minute. If the head of the water is 10 ft., 
calculate the power which could be obtained from a water 
motor, assuming the various losses in the motor as 30 per cent, 
and the average stream velocity 0.80 of the float velocity. 

211 



212 



FARM MOTORS 



The area of the cross-section of the stream = 10 X 4 = 40 ft. 
The quantity of water available per second is equal to 

40 X % X 0.80 = 16 cu. ft. 

As the weight of a cubic foot of water is 62.4 lb. at ordinary 
temperatures, the weight of water delivered to the motor per 
second is 

62.4 X 16 = 998.4 lb. 

The work done by the water is 

998.4 X 10 = 9,984 ft.-lb. 







Fig. 206. — Water measurement by weir. 

One horsepower is equal to 33,000 ft.-lb. per minute, or 550 ft.- 
lb. per second; allowing 30 per cent, for friction, the power 
available is 

9,984(1 - 0.30) 



550 



12.7 hp. 



Another method for finding the quantity of water available 
in a stream, called the weir-dam method, is illustrated in Fig. 206. 
A notch is cut in a thick board placed at some point in the 
stream. 

The length of the notch should be less than two-thirds the 



WATER MOTORS 213 

width of the board. The bottom of the notch is called the crest 
of the weir, and the depth of the water at that place should 
be more than three times the depth of the water flowing over 
the weir. The crest of the weir should be perfectly level and 
should be beveled on the downstream side. The edges of the 
notch should be beveled also on the same side. In the 
stream back of the weir, and at a distance somewhat greater 
than the length of the notch, a stake is driven level with the 
bottom of the notch or crest of the weir. When the water is 
flowing over the weir, measure the height of water above the 
top of the stake. If this height in feet is called H and the width 
of the notch in feet B, the quantity of water Q flowing through 
the stream, in cubic feet per second, can be determined by the 
formula : 

Q = 3.33 BH\/H 

As an illustration, if the width of the notch is 4 ft. and the 
depth of water on the weir is 12 in. the quantity of water avail- 
able per second is 

Q = 3.33 X 4 X j|J|| = 13.32 cu. ft. 

Since 1 cu. ft. of water = 7.48 gal., the quantity of water de- 
livered in gallons is 

13.32 X 7.48 - 99.6 gal. 

Types of Water Motors. — The water motors mostly used at 
the present time are waterwheels, which are made to revolve 
either by the weight of water falling from a higher to a lower level, 
or by the dynamic pressure which is produced by changes in the 
direction and velocity of flowing water. 

Reciprocating water motors are used to a limited extent for 
special purposes. Any steam engine with slight modifications 
can be used as a reciprocating water motor, but would run at 
slow speed on account of the incompressibility of water. 

Overshot, Undershot and Breast Wheels. — The earlier water 
motors derived their power from the weight of water acting on 
vanes placed around the rim of a wheel. 

Of these the overshot wheel receives its power from the weight 
of water carried by buckets on the circumference of a wheel, .the 



214 



FARM MOTORS 



water entering the buckets near the top of the wheel and being 
discharged near the bottom (Fig. 207). A wheel of this type can 
be constructed easily by inserting between two wooden discs a 
number of buckets, made like V-shaped troughs (Fig. 207), and 
putting a wooden or metal shaft at the center of the discs. 
Water is supplied from an open trough near the top of the wheel. 
Motors of this character can be built to operate on falls as low 
as 4 ft. and will supply from 3 to 50 hp., depending on the head 
of the fall and on the quantity of water available. 




Fig. 207.— Overshot 
water wheel. 




7W/, 



I I 

*5 V-////////////777777? 




Fig. 208.— Undershot 
water wheel. 



Fig. 209.— Breast 
water wheel. 



The undershot wheel is propelled by water passing beneath 
it in a direction nearly horizontal, which impinges on vanes 
carried by the wheel. Such wheels have been used to some ex- 
tent for irrigation work. Some of the undershot wheels have 
straight flat projections for vanes (Fig. 208), but the more effi- 
cient wheels are built with curved vanes. Such motors are suit 
able for very low falls, provided the velocity of the water is great. 

The breast wheel (Fig. 209) receives water at or near the level 
of its axis, but is otherwise quite similar in its action to the over- 
shot wheel. Breast wheels are provided with either radial 
vanes, or with vanes slightly curved backward near the 
circumference. 

All these wheels are very bulky for the power developed, as 
compared with the more modern types of impulse water motors. 

Impulse Water Motors. — Impulse water motors are provided 
with buckets or cups around the circumference of a wheel, which 
are acted upon by a jet of water issuing from a nozzle. 

Among impulse water motors, the Pelton wheel illustrated 
in Fig. 210 is used to a considerable extent in the United 
States. It consists of a series of cups or buckets B placed at 



WATER MOTORS 



215 



equal intervals around the circumference of an iron wheel. 
The characteristic feature of the Pelton motor is the shape of 
the buckets. These are made in the form of two half cylinders 
with closed ends, joined together at the center by a straight 




Fig. 210. — Pelton water wheel. 

thin rib. The power is derived from the pressure of a head of 
water supplied by a pipe which discharges upon the buckets of 
the wheel. The water from the nozzle N striking the rib, divides 




Fig. 211. — Water motor. 



into two streams, one going into each half cylinder and exerting 
a pressure on the curved surfaces of the buckets. The Pelton 
water motor usually is furnished with two nozzle tips of dif- 
ferent diameters. By changing the tip, the size of the stream on 



216 



FARM MOTORS 



the wheel is altered and a great variation in power may be 
obtained. 

Pelton water motors can be secured in very small sizes under 
1 hp. and up to several hundred horsepower. The efficiency 
of this type of motor is greatest at high heads, but in small sizes 
it will be found as efficient as most water motors, even for 
heads as low as 15 ft. 

Another type of water motor illustrated in Fig. 211 is made in 
sizes less than }4 hp. and can be used for running washing 




Fig. 212.— Water turbine. 

machines, sewing machines, grindstones, fans, small feed grinders, 
and for other purposes requiring little power. 

An impulse^water motor can be operated from city water mains 
or from an independent stream. 

Water Turbines. — A water turbine is a water motor which 
is made up of a number of stationary and movable curved 
pipes. It. consists of the following parts : 

1. A gate by means of which the supply of water to the tur- 
bine is regulated. 



WATER MOTORS 



217 



2. A guiding element consisting of stationary blades, the func- 
tion of which is to deliver the water to the revolving element in 
the proper direction and with the proper velocity. 

3. A revolving element or rotor, consisting of vanes or buckets 




, ",-"/ . __:% •-■ •• . • '. 



m& 



Fig. 213. — Water-power installation. 

which are arranged in any one of several different ways around the 
axis of the motor. 

Water turbines are divided into radial outward-flow, radial 
inward-flow and mixed-flow types. 

In the radial outward-flow turbine the water is received at the 



218 



FARM MOTORS 



center and is delivered at the periphery of the revolving buckets. 
In the radial inward-flow types the stationary or guiding element 
is located on the outside of the revolving part, and the water 
flows from the rim toward the center. 

The advantages of turbines over impulse wheels lie in the fact 
that a turbine can be utilized for very low falls. The turbines 
illustrated in Figs. 212 and 213 can be used on falls as low as 4 ft. 
and will develop about 3 hp. with a water supply of about 500 
cu. ft. per minute. 

The general appearance of a water-power installation with 
vertical turbines is shown in Fig. 213. 

The Hydraulic Ram. — The hydraulic ram combines in one 
simple machine a motor and a pump. It is probably the simplest 




l 1 



Fig. 214. — Hydraulic ram. 

and most economical method for supplying water for the farm 
house, the feed yard, the barn and the dairy where conditions are 
favorable. It can also be used to advantage, under certain con- 
ditions, for irrigating small tracts of land. 

Hydraulic rams are low in first cost and inexpensive to operate. 
They are not economical in water, as a large amount of water 
must be wasted in comparison with the work done. 

The working of the hydraulic ram depends on the fact that the 
momentum of a large quantity of water falling through a small 
height is capable of lifting a small quantity of water to a consider- 
able elevation. 

A section of a hydraulic ram is shown in Fig. 214. It consists 
of a working valve V, a check valve D, an air chamber C, a drive 
pipe A which supplies water to the ram, and a delivery pipe B 
which carries the water to the place where it is utilized. 



WATER MOTORS 



219 



The ram is located at a place where a fall of 2 to 10 ft. can be 
obtained. The water from the source enters the drive pipe (A in 
Fig. 214) and flows through the working valve V. The velocity 
of water in this pipe increases and when a certain velocity is 
reached, the pressure of the water on the under side of valve V 
is sufficient to close it abruptly. The flow of the water through 
the working valve being interrupted, the pressure increases and 
causes the check valve D under the air chamber C to open, and 
a part of the water is forced into the air chamber compressing the 
air in that chamber. The velocity of the water in the drive pipe 




Fig. 215. — Hydraulic ram. 

having been arrested, a recoil or ramming takes place, the pres- 
sure in the space below the air-chamber check valve D is reduced, 
thus closing the check valve D and allowing the working valve to 
open. The operations are then repeated. The delivery pipe 
to the storage tank at a higher elevation is attached to the air 
chamber below the water level. The air under compression in 
the air chamber forces the water in a steady stream through the 
delivery pipe B and to the storage tank. Hydraulic rams are 
also provided with a sniffing valve, not shown in the figure, the 
function of which is to replace any air in the air chamber, lost by 
being dissolved in the water. 

A hydraulic ram is illustrated in Fig. 215. A is the drive pipe, B 
the discharge pipe, C the air chamber and 7 the working valve. 



220 FARM MOTORS 

Problems: Chapter VIII 

1. What determines the power available in a stream? 

2. Calculate the horsepower available in a stream 24 ft. wide and 6 ft. 
deep, if the head of the water is 14 ft. and the velocity of the water is 20 ft. 
per minute. Assume the losses in the water motor equal to 25 per cent. 

3. Give directions for constructing a standard weir suitable for measuring 
water. 

4. Calculate the gallons of water flowing over a weir of the following 
dimensions: width of notch 3 ft., depth of water on the weir 15 in. 

5. Explain, using clear sketches, the Pelton waterwheel. 

6. What are the fundamental parts of a water turbine? 

7. Explain, using clear sketches, the construction and action of the 
hydraulic ram. 

8. Report on the future of water power for rural communities. 



CHAPTER IX 
WINDMILLS 

Types of WindmDls. — The windmill is a motor which converts 
the kinetic energy of the wind into useful work. 

Some of the earlier windmills were constructed with sails 
which consisted of wooden frames, the broad sides of which were 
covered with cloth. These sails were turned by the wind in 
horizontal or vertical planes. One of these mills, the Dutch 
type, is illustrated in Fig. 216. As the direction of the wind 
changed, the entire wheel-house, including shafting and ma- 
chinery, was rotated on a pivot so as 
to bring the wheel to face up to the 
wind. This limited the size of the 
mill. In the latter types of the 
Dutch mill, only the upper part of 
the wheel-house was rotated. These 
mills were governed by varying the 
extent of the sail surface exposed to 
the wind, while the wheel was at rest. 

The Dutch types of wooden mills 

c i t_ j. u 11 j Fig. 216. — Dutch windmill, 

are powerful, but bulky and expen- 
sive. They are but little used in this country at the present 
time. 

The American mill is made up of a great number of narrow 
blades or fans. This means a mill of smaller weight and less bulk 
than the Dutch mill of the same power. 

Windmills may be classified as pumping and power windmills. 
The pumping windmill gives a reciprocating motion to a vertical 
rod suitable for operating a pump, while the power windmill 
gives rotary motion to a shaft through a train of gears. 

The wheel and rudder of American windmills are constructed 
either of wood or of steel. The best steel windmills are galvan- 
ized for protection from rust. 

Windmills are designated by the diameter of the wind wheel. 
Thus the so-called 15-ft. mill has a wheel 15 ft. in diameter. 

221 




222 



FARM MOTORS 



American windmills are built either as direct-stroke or as back- 
geared. In the case of the direct-stroke windmill the main 
shaft carries a crank which is attached to the pump rod by a con- 
necting rod, commonly called the pitman, there being no speed- 
reducing gears. In this type, the pump makes one complete 
stroke for each revolution of the wind wheel. Geared mills are 
back-geared, so that the pump makes one stroke for every 
three or five revolutions of the wind wheel. The back-geared 
mill will develop more power than the direct-connected mill for a 
wind wheel of the same diameter. 

Principal Parts of a Windmill. — The principal parts of a wind- 
mill are: 





Fig. 217.— Wind wheel. 



Fig. 218. — Hub of wind wheel. 



1. A wind wheel which receives the kinetic energy of the wind. 
This wheel is carried upon the main shaft. 

2. A rudder or vane which steers the wheel against the wind. 

3. A governor, which regulates the speed of the wind wheel. 

4. Gearing. 

5. A brake which holds the wheel stationary when out of the 
wind. 

6. Main casting which supports governor, gearing and brake. 
This with the parts which it supports is called the mill head. 

7. A tower which is a support for the mill. The tower should 
be tall enough to raise the wheel sufficiently high above all ob- 
structions, such as trees, houses, etc., that it will receive a 
steady breeze. 



WINDMILLS 



223 



The Wind Wheel. — The wind wheel (Fig. 217) is that part of 
the mill which derives the energy from the wind. 

The hub of the wheel either consists of two separate wheel spi- 
ders (Fig. 218) keyed to the main shaft, or it is constructed as a 
solid casting with the wheel spiders at either end. 

The arms or spokes of the wheel (S in Fig. 217) are attached 
to the wheel spiders (P) and extend outward to the rim R. The 
spokes are usually of rectangular or circular cross-section, but 
some manufacturers use steel angles. 

The rims are placed, one near the inner ends of the fans F, and 
the other either a little beyond the center or near the outer ends of 
the fans. The rims are made either of strap steel or of angle 
steel. 





Fig. 219. — Fans of windmill. 



Fig. 220. — Samson wheel. 



The fans (Figs. 217 and 219) are so curved that the wind on 
leaving one fan will not strike upon the back of the next. The 
spacing of the fans is such that the wind passes through freely 
and all parts of the wheel must be so designed as to offer the 
least resistance to the wind. The fans are fastened to the rims 
by brackets and the various sections of fans and rims are riveted 
together. 

Fig. 220 shows a Samson wheel with strap steel spokes and 
hollow hub. 

The general construction of a wooden wind wheel is similar 
to that of the steel wheel, except that the spokes, rims and fans 
are of wood. The rims are made either straight from spoke to 



224 



FARM MOTORS 



spoke or are bent in a manner similar to that of steel mills. A 
section of a wooden wind wheel is illustrated in Fig. 221. The 
wooden wind wheel is made up of six or more sections, each sec- 
tion consisting of 15 or more slats. 

The Rudder or Vane. — Most windmills are provided with 
some form of rudder or vane for keeping the wheel in the direc- 




Fig. 221. — Section of wooden wind wheel. 

tion of the wind. In some windmills no rudder is employed, and 
the pressure of the wind on the wind wheel is relied upon to 
bring the wheel in the right direction. Windmills without 
rudders are provided with folding wheel fans and have a weighted 




Fig. 222.— Steel rudder. 




Fig. 223.— Wood rudder. 

ball which performs the function of a rudder and opens the 
wheel when the wind is greater than the load. Then some of the 
larger windmills without rudders are provided with a small side 
wheel which is set perpendicular to the wind wheel, and turns 
the wind wheel into the proper direction by means of gearing. 

The rudder is built either of steel (Fig. 222) or of wood (Fig. 
223). 



WINDMILLS 225 

It is often desired to throw the wind wheel out of action. This 
in the case of the folding wheel is accomplished from the ground 
level by a wire or rod which extends up through the tower 
and connects with a system of levers which tip the sections of 
the wheel. The solid wheel is thrown out of action either by 
pulling it around parallel with the vane, so that its edge faces 
the wind, or by pulling the vanes parallel to the wind. 

The Governor. — The function of a governor is to regulate the 
speed of the wind wheel. 

In some windmills the governor consists of a coiled spring, 
one end of which engages with the rudder and the other with the 
mill head. When the wind pressure becomes too great, the 
wheel will swing so as to expose less surface to the wind. 

To assist in governing, some mills are provided with a side vane. 

In the case of folding-wheel mills the angle of the fans is 
changed, by a system of weights and levers, according to the 
intensity of the wind. 

Most windmills are provided with a " pull-out reel," which 
consists of a ratchet and windlass for throwing the wind wheel 
out of action. When the ratchet is released the wind wheel is 
thrown into correct position by the rudder and governor. Some 
windmills use a lever instead of a ratchet and windlass for the 
same purpose. 

Windmill Gearing. — The gearing of a direct-stroke windmill 
is illustrated in Fig. 224. 

One simple form of a back-geared mill mechanism is given in 
Fig. 225. E represents the hub of the wind wheel. The pinion 
P is carried on the main shaft and meshes with a large gear A on a 
countershaft. The center of the gear A is placed to one side of 
the upper end of the connecting rod or pitman B, so that it 
requires more than half of a revolution to raise the pump rod and 
less than half of a revolution to lower it. Thus a quick return 
motion is obtained, the pump rod descending more rapidly than 
it rises. This is advantageous in that little power is required 
on the down-stroke, there being no water raised and the weight 
of the plunger, pump pole and pump rod being sufficient to 
produce that stroke. The slow motion on the up-stroke enables 
the mechanism to carry the load with the least strain. In this 
mechanism D is a hinge for attaching the rudder or vane. 

15 



226 



FARM MOTORS 



The difference in construction between the gearing for pump- 
ing and power windmills is in the addition of a bevel gear B 
(Fig. 226) which meshes with another bevel gear on the power 
shaft. 

All windmills should be provided with some form of buffer to 
protect the rudder and other parts from sudden shocks when the 
windmill is thrown out of gear. The buffer is usually constructed 





Fig. 224. — Direct-stroke windmill. 



Fig. 225. — Back-geared windmill. 



in the form of a helical steel spring placed upon the rudder rail 
near the hinge. 

Windmill Brake. — Nearly all windmills are provided with an 
automatic brake, which holds the wheel stationary when out of 
the wind. The brake is a flexible steel band which encircles 
about three-fourths of the flange on the hub of the wind wheel 
and holds it stationary when out of gear. The brake is applied 
by a lever as soon as the windmill is turned out of gear. 

Towers. — Windmill towers are constructed either of wood or 
of steel. 

There are a great many different kinds of wooden towers, as 



WINDMILLS 



227 



they are often " home-made." Four 4-in. by 4-in. or 6-in. by 
6-in. timbers, depending on the size of the tower, are most com- 
monly employed for the corner posts. They are spread about 
8 or 10 ft. at the bottom and are brought together at the top 
and fastened to a cast-iron cap, usually provided by the manu- 
facturer. A platform 2 or 3 ft. square should be provided 
directly below the wind wheel for the purpose of facilitating 
oiling, inspection and repairing. The tower ends of the corner 




Fig. 226.— Power windmill. 



posts are bolted to anchor posts which are set about 6 ft. in the 
ground with cross-pieces bolted to the lower end to form a 
better foundation. 

Steel windmill towers are built with either three or four 
posts and should always be galvanized and not painted. A tower 
supported on four posts (Fig. 227) is protected from a wind in 
any direction. The three-post tower (Fig. 228) is somewhat 
cheaper than the four-post tower, and has the additional advan- 



228 



FARM MOTORS 




Fig. 227. — Four-post tower. 



WINDMILLS 



229 




Fig. 228.— Three-post tower. 



230 FARM MOTORS 

tages, in localities where the ground is soft, of always standing 
firm and rigid, and of being unaffected by unequal settling of 
anchor posts. A three-post tower when properly braced also is 
stiffer and stronger than a four-post tower. 

The corner posts of a steel tower are usually of angle steel, 
but some are of gas pipe. The cross-girts are of angle steel and 
the braces may be of angle steel, rods, or wire cable. The anchor 
posts are about 6 ft. long and of the same material as the corner 
posts, with anchor plates attached at the lower end. 

The method of fastening the corner posts of three- and four- 
post towers is shown in Fig. 229. The posts are beveled, notched 
and are held together by clamps and bolts. 





Fig. 229. — Method of fastening corner posts of three-post and 
four-post towers. 

The tower in Fig. 230 has the lower braces of angle steel and 
the other braces of rods. Twisted-wire cable braces are shown 
in Fig. 231. 

Method of Erecting Windmills. — A windmill is erected either 
by building it up in position piece by piece, or it is assembled 
on the ground and then raised into position. The method of 
raising a windmill from the ground is illustrated in Fig. 232. 

After the holes for the anchor posts are dug, the anchor posts 
are placed loosely in them. In raising towers over 30 ft. in 
height, the lower portion should be reinforced by placing timbers 
in the tower (Fig. 232). A beam of wood is then placed across 
the lower ends of the legs, and stakes are driven at each end, in 
order to prevent the tower from sliding when it is being raised. 
A strong rope is attached to the tower near the platform and to 



WINDMILLS 



231 




Fig. 230. — Tower of aermotor windmill. 





a 




Fig. 231. — Twisted wire braces. 



232 



FARM MOTORS 





Fig. 232. — Method of raising windmill from the ground. 



WINDMILLS 233 

a block and tackle a little beyond the lower end of the tower. 
Another block is made fast to some stakes driven at a distance 
of one and one-half times the length of the tower from the lower 
end of the tower. Shear poles about one-half the length of 
the tower are then placed under the rope near the lower end 
of the tower. Stakes are driven at each side of the upper 
end of the tower, to which ropes are attached to retain the tower 
in position, and the tower is pulled into position by a traction 
engine, team, or windlass. Several men usually can raise a small 
tower by pulling directly on the tackle rope. 

When the tower is nearly erect, the two front anchor posts 
should be bolted on and the rear guy line payed off until the two 
anchor posts come into place on the bottom of the holes. The 
tower is then tilted back and the other two anchors are attached 
in the same way. 

After the tower is in position it should be leveled with a 
plumb bob, before the pump rod is put into place. All braces 
must be evenly tightened. 

Loose stones are often placed below and above the anchor 
plate. For best results a concrete base should be used. When 
using loose stones, it is desirable that the anchor plates should 
rest on cap stones. 

Care of Windmills. — A windmill requires some care if long 
and good service is expected. 

When first erected it should be carefully examined every few 
days for loose bolts and bearings. 

All bearings should be kept well-lubricated and brasses tight. 
If anchor posts work loose, they should be reset. It is always 
well to shut down a windmill during a heavy storm. 
. Windmills may be lubricated by means of oil cups, the oil 
being held in place by waste. With the ordinary oil cups a 
windmill would have to be lubricated every 2 or 3 days if it were 
running continuously. To reduce the necessity of frequent 
lubrication, some form of self-feed oil cup is used. This consists 
of a large oil cup with a tube extending nearly to the top of 
the oil cup. A twisted-wire wick passes from the bottom of 
the oil cup into the tube. The oil from the cup follows the wick- 
ing into the tube and lubricates the bearing which is at the 
bottom of the tube. 



234 



FARM MOTORS 



Power of Windmills. — The power delivered by a windmill 
depends on the velocity of the wind, on the size and construction 
of the wheel, on the amount of power lost in friction and on the 
density of the air. 

It has been found that an average wind velocity of 6 miles per 
hour is required to drive a windmill. The average velocity of 
the wind in the United States varies from 4.2 to 16 miles per 
hour. The best wind velocity is about 15 miles per hour. 
The velocity in most localities is great enough to operate a mill 
about 8 hr. per day. 

The power developed by a windmill with winds of average 
intensity will vary from }i hp.. for a 6-ft. wind wheel to about 
1 hp. for a 16-ft. wind wheel. With strong winds and with 
large wheels, windmills will develop as much as 4 hp. 



Table 7.- 


—Power of Windmills 


Wind velocity, miles per hour 


Indicated horsepower 












12-ft. wheel 


16-ft. wheel 


8 




0.10 


0.18 


10 




0.20 


0.36 


12 




0.34 


0.60 


15 




0.67 


1.21 


20 




1.60 


2.90 


25 




3.12 


5.50 


30 




5.40 


8.50 



The angle and spacing of the wind-wheel fans affect the power 
delivered by a windmill. Then the quality and condition of the 
gearing and bearings determine the actual power available for 
utilization either at the pump or power shaft. 

The density of the air affects the pressure of the wind on the 
wind wheel. Thus the higher the altitude the lighter is the air 
and the less power is developed with a wind of a certain velocity. 

The cost of windmill power is about 5 cents per horse power 
per hour, when considering cost of attendance, repairs, cost of 
lubrication and interest on investment. 

Uses of Windmills. — The main use of windmills is for pumping 
water for domestic use and for stock. When used in pumping 



WINDMILLS 235 

water for irrigation, a storage tank of large capacity should be 
provided, sufficient for several days' use in case of calm weather. 

For watering stock on small farms and for domestic use on the 
farm, the windmill is the cheapest and best form of motor. It 
requires but little attention. One-half hour per week devoted to 
oiling and inspection will keep the mill in good condition. 

A windmill cannot be used for heavy work on the farm, but 
can drive small feed grinders, grindstones, corn shellers, feed 
cutters, wood saws, churns, or any other machine requiring little 
power. 

In general the windmill is suitable for work requiring but little 
power, which will admit of suspension during calm weather. 

Problems: Chapter IX 

1. Explain the Dutch type of windmill. Why is this type of mill not 
used in the United States? 

2. What are the principal parts of a windmill? 

3. How are windmills rated? 

4. Explain the construction of the wind wheel. 

5. What is the function of the vane or rudder? 

6. Explain construction and action of some type of windmill governor. 

7. Explain in detail the action of the direct-stroke windmill illustrated in 
Fig. 224. 

8. Show by means of sketches or illustrations the difference between the 
power windmill and the windmill which is designed for pumping only. 

9. Give directions for building a modern windmill tower. 

10. Compare the advantages and the disadvantages of the three-post and 
the four-post windmill tower. 

11. Give directions for erecting a windmill. 

12. Report on the uses of the windmill for irrigation and for the genera- 
tion of electricity. 



CHAPTER X 
GENERATORS, ELECTRIC MOTORS AND BATTERIES 

Before considering the various types of electric motors and their 
applications, the fundamentals of electricity and of dynamo 
electric machinery will be taken up. 

Action of Electricity. — The action of electricity in an electric 
generator is analogous to that of water pumped from a lower to 
a higher level. The function of a pump in forcing water through 
pipes is well known. The pump exerts a pressure on the water. 
If the pressure exerted by the pump is doubled, the quantity of 
water handled by the pump will also be doubled, if the friction of 
the water through the pipe remains the same. It is also well 
known that the resistance offered to the flow of water through 
pipes increases with the length of the pipe. Also by increasing 
the size of the pipe the resistance is decreased. 

The generator in the electric power plant performs a function 
similar to that of the pump. It generates electrical pressure in 
order to send electricity through the wires which correspond to 
pipes. The resistance offered by the wire to the flow of electricity 
is analogous to that offered by the water pipe to the flow of water. 
The quantity of electricity delivered to the circuit, which may 
consist of motors, lamps, or other appliances using electricity, 
corresponds to the amount of water delivered by the pump to an 
overhead tank or pipe from which water motors or other appli- 
ances requiring water under pressure can be operated. 

Units of Electricity. — The pound is the unit of water pressure, 
while the unit of electricity is the volt. The amount of water 
flowing through a pipe is measured in gallons per minute, the 
quantity of electricity flowing through a wire in amperes. The 
resistance which a wire offers to the flow of electricity is measured 
in ohms. 

The unit of electrical power is the watt, a watt being the prod- 
uct of a volt and ampere. The power available in a certain 
weight of water depends on the head, or on the distance the 

236 



GENERATORS, ELECTRIC MOTORS, ETC. 237 

water is allowed to fall. Similarly the power available at the 
terminals of a generator is the product of the quantity of elec- 
tricity in amperes and the electrical pressure head in volts. 

As an illustration, the power available at the terminals of a 
generator delivering 60 amp. at 110 volts is 

Power in watts = 60 X 110 = 6,600 

Generators usually are rated in kilowatts (kw.), a kilowatt 
being 1,000 watts. Electric motors are rated in electrical horse- 
power, an electrical horsepower being equal to 746 watts. The 
relation between the kilowatt and the electrical horsepower is 

746 /s ' 

Thus an electric motor operating on a 220-volt circuit and 
requiring 30 amp. has delivered to it 

— =rr^ — = 8.85 electrical horsepower. 

If the efficiency of the motor is 80 per cent., the available power 
at the motor shaft is 8.85 X 0.80 = 7.08 b. hp. 

Ohm's Law. — The law expressing the relation between the 
volt, the ampere and the ohm is of great value in electrical 
calculations. It is called Ohm's law and is expressed by the 
statement that 

ml , . Pressure in volts 

The current in amperes = ^ — ^r = r — 

^ .Resistance m ohms. 

Expressing the current by the symbol I, the voltage by E and 
the resistance by R 

I = E 

1 R 

As an illustration, an ordinary 16-cp. carbon lamp operating 
on a 110- volt circuit offers a resistance of 220 ohms. How much 
current will be required to operate the lamp? 
Applying Ohm's law — 

_ E _ 110 volts _ 1 
1 ~ R ~ 220 ohms ~ 2 amp * 

The power required to operate the lamp is 
110 X 2 = 55 watts. 



238 



FARM MOTORS 



Considering no losses in the engine, generator and lines, the num- 
ber of 16-cp. carbon lamps which can be operated by a generator 
driven from a 1-hp. engine is 
746 



55 



13.56 lamps. 



Due to line losses and to losses in the generator, it is customary 
to figure about ten 16-cp. carbon-filament lamps per engine 
horsepower. 

Incandescent Lamps. — Table 8 shows the current consumed 
by carbon-filament and by tungsten-filament lamps of various 
candlepowers. From this table it is evident that the tungsten- 
filament lamp consumes about one-third the current required 
by carbon-filament lamps of the same candlepower. A tungsten- 
filament lamp will require about 1.25 watts per candlepower 
and will give a whiter light than the carbon-filament lamp. 

Table 8. — Current Consumed by Incandescent Lamps at 110 Volts 



Candlepower 


Amperes 


Watts 


Carbon 


Tungsten 


Carbon 


Tungsten 


8 
16 
20 
32 

48 


0.25 
0.50 

1.00 


0.228 
0.364 
0.545 


28 
55 

110 


25 
40 
60 



Wires for Conductors of Electricity. — The resistance which 
a wire offers to the flow of electricity depends on its cross-section 
and on the material from which it is made. Silver when pure 
is considered to be the best conductor. Copper is very nearly 
as good a conductor as silver, and, being much cheaper, it is 
used in nearly all cases for the distribution of electricity. 

Copper wire is sometimes used bare, but in most cases it is 
covered with a material called insulation, to prevent the transfer 
of electricity to surrounding substances. The insulation used 
on wire is either rubber or some weather-proof substance. 

Copper wires are designated either by the Brown and Sharpe 
wire gage (B. & S. gage) or by their cross-section in circular 
mils. A circular mil is a circle Kooo m - m diameter. The 



GENERATORS, ELECTRIC MOTORS, ETC. 239 



designation of wire by the B. & S. gage is more common for small 
wires. This gage is constructed so that the numbers decrease 
as the size of the wire increases. Thus a No. 10 B. & S. wire is 
smaller than a No. 9 and larger than a No. 11. 

The current-carrying capacities in amperes of various sizes 
of rubber-covered and weather-proof wire are given in Table 9. 

Table 9. 



Size of copper wire 


Current-carrying capacity in amperes 


B. & S. gage 


Circ. mils 


Rubber-covered wire 


Weather-proof wire 


18 

16 

14 

12 

10 

8 

6 

5 

4 

3 

2 

1 



00 

000 

0000 


1,624 

2,583 

4,107 

6,530 

10,380 

16 ? 510 

26,250 

33,100 

41,740 

52,630 

66,370 

83,690 

105,500 

133,100 

167,800 

211,600 


3 

6 

12 

17 

24 

33 

46 

54 

65 

76 

90 

107 

127 

150 

177 

210 


5 

8 

16 

23 

32 

46 

65 

77 

92 

110 

131 

156 

185 

220 

262 

312 



The sizes of wire in the tables are given in terms of the B. & S. 
gage as well as in circular mils. 

Electrical Batteries. — Batteries are used mainly in places 
where the current requirement is small, as in connection with 
the ignition systems of internal-combustion engines, also for 
operating telephones, telegraphs, electric bells, etc. 

Batteries can be called chemical generators of electricity, and 
are of two types. One type, called the primary battery, generates 
electrical current by means of direct chemical action between 
certain substances. Another type, called a secondary battery 
or storage battery, requires charging with electricity from some 
outside electric source before it will generate electrical energy. 
The outside current acting on the substances within the battery 



240 FARM MOTORS 

changes their chemical properties to such an extent that the 
battery is able to deliver current when connected to a circuit. 
After storage batteries furnish current to a circuit for a certain 
length of time, their active materials become nearly exhausted 
and they must be recharged with electricity before they can be 
used again. Here lies the difference between the storage 
battery and the ordinary primary battery. The active materials 
in the primary battery when once exhausted cannot be brought 
back to generate electricity, and must be renewed. 

The term battery is applied to two or more cells, whether 
primary or storage types, which are connected together to in- 
crease the total amount of electrical energy delivered to a 
circuit. 

Primary Batteries. — A primary cell consists essentially of a 
vessel containing some acid called the electrolyte in which are 
immersed two solid conductors of electricity, called electrodes, 
one of which is more easily attacked by the acid than the other. 
A simple cell consists of a weak solution of sulphuric acid, as 
an electrolyte, a plate of zinc, which is easily decomposed by the 
sulphuric acid, and a plate of some other solid like copper or 
carbon which resists the action of sulphuric acid. If the plates 
of zinc and copper are put side by side in a vessel containing 
sulphuric acid, and the circuit is completed by joining the two 
plates by a wire, chemical action will be set up within the vessel 
or cell. The zinc will dissolve in the acid, forming zinc sulphate, 
hydrogen will be given up by the sulphuric acid in streams of 
bubbles which will settle on the copper plate, and a current of 
electricity will be generated. The bubbles of hydrogen liberated 
from the electrolyte do not combine with the copper plate, but 
form a gaseous non-conducting film over the metallic surface 
which increases the resistance of the cell to the flow of electric 
current. The formation of the bubbles of hydrogen on the copper 
plate, called polarization, causes a rapid falling off in the power. 
It is possible to decrease or even eliminate polarization. One 
good method is to construct the cell with some strong oxidizing 
agent. The oxidizing agent gives up its oxygen, which combines 
with the particles of hydrogen, forming water and decreasing 
polarization. Cells using this method of decreasing polarization 
usually employ carbon plates, as most of the oxidizing materials 



GENERATORS, ELECTRIC MOTORS, ETC. 241 

attack copper plates. The Leclanche cell shown in Fig. 233 is 
an example of this type of cell. 

The dry cell, which is used extensively at the present time on 






Fig. 233. — Leclanche cell. 



Fig. 234.— Dry cells. 



account of its portability, is a modification of the Leclanche cell. 

It has zinc for the positive electrode, carbon for the negative 

electrode, sal ammoniac and zinc chloride as the electrolyte for 

decomposing the zinc, and some oxidizing 

agent like manganese dioxide to eliminate 

polarization. As usually constructed, the 

dry cell consists of a zinc cylinder which is 

the positive electrode and acts at the same 

time as a container for the other materials 

of the cell. The zinc cylinder is provided 

with a lining composed of plaster of paris, 

flour, blotting-paper, or some other absorbent 

material saturated with sal ammoniac and 

zinc chloride. At the center of the cell is a 

carbon rod, and this is surrounded by a 

paste consisting of manganese dioxide and 

chloride of zinc. The top of the cell is ^ 

• ii ,- i i • i * 7, Fig. 235. — Edison 

covered with a layer of hard pitch. A small Lalande cell. 

hole through the pitch permits the escape of 

gases which may be formed within the cell. The outside of 

the cell usually is insulated with paper. Several forms of 

dry cells are illustrated in Fig. 234. The solution in the dry 

16 




242 FARM MOTORS 

cell evaporates slowly, so that a battery of dry cells will be- 
come worthless after a certain time even if it is not used. 
Generally a dry cell in good condition will have a current 
strength of 15 to 25 amp. and should show a pressure of 1)4 to 
1}^ volts. A binding post is attached to the carbon and 
another one to the edge of the zinc cylinder. 

The various Lalande wet cells are very good for gas-engine 
ignition. One form, the Edison Lalande, is illustrated in Fig. 
235. One electrode in this cell is of zinc and the other of copper 
oxide. The electrolyte consists of caustic potash. The oxygen 
of the copper oxide prevents polarization. A film of heavy 
paraffin oil is put on top of the electrolyte, so as to prevent the 
absorption of carbon dioxide from the air by the caustic potash. 

Storage Batteries. — A storage battery consists of two sets of 
plates or electrodes known respectively as positive and negative, 
submerged in a liquid called the electrolyte. The plates are 
encased in a jar or container. This type of battery must be 
charged frequently with electricity in order to give out current to 
the external circuit. The storage battery does not store elec- 
tricity, but energy in the form of chemical work. The electric 
current produces chemical changes in the battery and these 
changes produce a current in the opposite direction when the 
circuit is closed. 

Storage batteries are used for gas-engine ignition and are pre- 
ferred for this purpose to primary dry or wet batteries on account 
of their greater capacity and more uniform voltage. Modern 
automobiles, as explained in Chapter VI, employ storage batter- 
ies for starting, lighting and ignition. Storage batteries are also 
used to a considerable extent for farm lighting in order to shorten 
the time required for operating the engine and electric generator. 

The capacity of a storage battery is measured in ampere-hours 
determined by multiplying the current rate of discharge by the 
number of hours of discharge of which the battery is capable at 
that rate. As an illustration, a battery that will deliver 10 amp. 
for 8 hr. has a capacity of 80 amp.-hr. The ampere-hour capac- 
ity of a storage battery is dependent upon the rate of discharge. 
Most manufacturers specify the rate of discharge for their par- 
ticular make of storage batteries. If the rate of discharge is 
greater than the specified amount, the capacity of the battery is 



GENERATORS, ELECTRIC MOTORS, ETC. 243 

reduced. If a storage battery has a capacity of 80 amp.-hr. at 
the 10-amp. rate, it will have a greater ampere-hour capacity if 
discharged at a 5-amp. rate; that is, it will deliver a current of 5 
amp. for more than 16 hr. The normal rate of discharge is the 8- 
hr. period. 

A storage battery can be charged from any direct-current cir- 
cuit, provided the voltage of the charging circuit is greater than 
that of the storage battery when fully charged. Before a stor- 
age battery is connected to the charging circuit its polarity should 
be carefully determined, and the positive and negative terminals 
of the battery connected to the positive and negative terminals of 
the source respectively. One good method of determining the 
polarity of the wires from the storage battery or source is to 
immerse them in a glass of salt water. Bubbles of gas will form 
more rapidly on the surface of the negative wire. Another test 
is that the negative wire will turn blue litmus paper red. Should 
the positive wire of the battery be connected to the negative wire 
of the source, the effect would be a discharge of the battery, and 
this being assisted by the incoming current, a reversal of action 
would take place, which is very injurious to the battery. It is 
not well to charge a battery at too rapid a rate, as this will raise 
its temperature and will cause buckling of the battery plates. It 
is well also to charge batteries at regular intervals. 

Two types of storage batteries are used, the lead storage 
battery and the Edison. The Edison battery is also called the 
alkaline or the nickel-iron battery. 

The Lead Storage Battery. — In the lead storage battery both 
the positive and the negative electrodes of a cell are of perforated 
lead plates. The perforations are filled with certain lead com- 
pounds (Pb 3 4 and PbO) which react with the electrolyte of di- 
lute sulphuric acid, forming lead peroxide on the positive plate and 
a spongy metallic lead on the negative plate. The lead peroxide 
and the spongy metallic lead are both converted into insoluble 
lead sulphate (PbSO.0 when this cell delivers current, and this 
lead sulphate is converted back into lead peroxide and spongy 
lead respectively when a reversed current is forced through the 
cell. The lead peroxide and spongy lead are called the active 
materials of the cell. 

The voltage of the cell increases with the increased concentra- 
tion of its electrolyte, which is sulphuric acid. When the cell is 



244 



FARM MOTORS 



completely charged, the electrolyte is more concentrated and the 
voltage is large. As the cell is discharged, the concentration of 
the sulphuric acid is decreased and the voltage drops. 

A lead cell when fully charged will show 2.2 to 2.5 volts on 
open circuit and about 2.15 volts when the circuit is closed. A 
lead storage battery should not be allowed to discharge to a vol- 
tage lower than 1.8 volts while giving its full rated current. 

The storage cell is composed of an odd number of positive 
plates and of an even number of negative plates, so that each 
side of a positive plate faces a negative plate. The plates are 
insulated from each other and from the bottom and are placed in 
a glass vessel, if the battery is to be used for stationary purposes, 
and in a vessel of hard rubber if the battery is for portable use. 
Various forms of lead storage batteries are illustrated in Fig. 236. 




Fig. 236. — Lead storage batteries. 



The positive and the negative plates of a storage battery can be 
distinguished by their color. The positive plates, when fully 
charged, should have a dark brown or chocolate color, and the 
negative plates more of a light gray or a metallic lead color. 

Lead storage batteries deteriorate rapidly in service, if not 
properly cared for. 

For successful operation and long life, storage batteries should 
be tested frequently with a pocket voltmeter for voltage and 
with a hydrometer for the specific gravity of the electrolyte. A 
battery hydrometer for measuring the specific gravity is illus- 
trated in Fig. 237. The specific gravity of the electrolyte of a 
stationary battery should be 1.17 to 1.22 when the battery is 
fully charged A portable battery should have a greater specific 
gravity, and, when fully charged, this will vary from 1.275 to 



GENERATORS, ELECTRIC MOTORS, ETC. 245 

1.300. If too low, add stronger sulphuric acid until the correct 
specific gravity is obtained. 

Water must be occasionally added to the electrolyte to make up 
for evaporation. When water is added, this should be poured to 
the bottom of the cell through a long rubber tube attached to a 
funnel. The electrolyte level should be about }4 in. above the 



If a storage battery is to remain unused for any length of time, 
it should be discharged and immediately recharged about once per 




Fig. 237. — Battery hydrometer. 

week. To allow a storage battery to remain discharged for any 
length of time is injurious to the plates. 

The Edison or Nickel-iron Storage Battery. — The Edison 
storage battery consists of two sets of sheet-steel plates or grids, 
submerged in an electrolyte of caustic potash. The plates or 
grids support . tubes and pockets containing the active materials 
(Fig. 238). These grids have holes at the top which fit snugly 
over connecting rods on which the poles are forced by pressure to 
a perfect fit. The plates are held apart by spacing washers on 
the connecting rod. The positive plates are assembled on one 
connecting rod with the positive pole and the negative plates on a 
similar rod with the negative pole. 

The positive material of the positive plate is nickel hydrate. 
When the cell is charged, the nickel hydrate changes to a high 
oxide of nickel. 



246 



FARM MOTORS 



The active material on the negative plate is a specially prepared 
black oxide of iron. 

The plates are held in a steel container which eliminates 
the danger of broken jars. Hard-rubber insulation at the bot- 
tom and sides prevents electrical contact between plates and 
container. 

Edison batteries do not have as high capacity when new as 



.-FILLER CAP 



NEGATIVE POLE- 
HARD RUBBER GLANl 
CAP 

kCELL COVER 




(j- POSITIVE POLE 

COPPER WIRE 
--SWEDGED INTO 
i. STEEL LUG 
H '''CELL COVER WELDED 
TO CONTAINER 
STUFFING BOX 

H-WELD TO COYER 
J- GLAND RING 
K- SPACING HASHER 
\.- CONNECTING ROD 
M- POSITIVE GRID 
N- GRID SEPARATOR 
-SEAMLESS 

■ STEEL RINGS 
?- POSITIVE TUBE 
(NICKEL HYDRATE &\ 
\NICKEL IN LAYERS / 



CORRUGATIONS 



SUSPENSION BOSS 



Fig. 238. — Edison storage battery. 



after some weeks of use. This is due to the improvement of 
conditions in the nickel electrode, brought about by regular charg- 
ing and recharging. 

The voltage of an Edison cell when fully charged is less than 2 
volts, while that of the lead cell is more than 2 volts. This means 
that more Edison cells will be required for a given voltage than 
lead cells. 

The cost of Edison cells and of the best grades of lead cells is 
about the same. The cost of an Edison battery for higher volt- 



GENERATORS, ELECTRIC MOTORS, ETC. 247 

ages is greater than that of lead batteries as the necessary number 
of cells for a given voltage is greater in an Edison battery. 

The Edison cell has a tight cover, a valve being provided 
for the escape of gas. Very little water is lost by ordinary 
evaporation. 

The normal strength of the electrolyte is 1.200, as measured by 
a hydrometer, but may at times be as high as 1.230. 

Methods of Connecting Batteries. — The various methods of 
connecting batteries are illustrated in Figs. 239 to 241. 

+— @=-@H©h- - 

ABC 

Fig. 239. — Batteries in series. 

In the series battery connection (Fig. 239) the positive ( + ) 
of one cell is connected to the negative ( — ) of the other cell. 
The voltage of the battery is equal to the sum of the voltage of the 

+ Terminal 




— Terminal 

Fig. 240. — Batteries in multiple. 

cells A, B, and C, while the current is equal to that of one cell 
only. If three storage cells, each having a pressure of 2.1 volts 
are connected in series, the pressure of the battery is 6.3 volts. 




Fig. 241. — Batteries in multiple-series. 

The multiple-battery connection method is illustrated in Fig. 
240. In this case the positive terminals are connected, as are also 
all the negative terminals of the battery. If the external resist- 
ance is low, the current of the battery is proportional to the 
number of cells, while the pressure in volts is equal to that of one 
cell only. 

Another method shown in Fig. 241 and called the multiple- 



248 FARM MOTORS 

series method of connecting batteries consists of connecting the 
battery in two sets, the cells of each set being connected in series 
and the two sets are connected in multiple. The effect of 
this method of connecting cells is that the total pressure of the 
system is equal to that of three cells and the current is equal to 
that of two cells. 

The Electric Generator. — The electric generator, popularly 
called a dynamo, consists essentially of an armature composed 
of coils of wire wound around an iron core, and one or more mag- 
nets. Either the armature or the magnets must be given motion 
by some form of motor with relation to the other before the gen- 
erator can generate a current of electricity. 

The magnet may be a permanent magnet or an electromagnet. 
The so-called " permanent magnet" is made of hard-tempered steel 
which, after having been brought under the influence of some mag- 
netizing apparatus, will retain a certain amount of magnetism. 
Permanent magnets are expensive to make in large sizes and do not 
hold their magnetism for any length of time. They are employed 
only in the construction of small electric generators called 
magnetos, which are used mainly in connection with electric 
ignition systems for gas engines, and for signaling work. 

Generators which generate electric current for commercial 
purposes employ electromagnets. An electromagnet consists of 
a piece of iron which has wound around it many turns of insulated 
copper wire. If a current of electricity is passed through the 
insulated copper wire, the iron becomes immediately magnetized, 
and remains magnetized as long as the current is passing through 
the wire. There is practically no limit to the strength of an elec- 
tromagnet, as this depends only on the number of turns of 
copper wire and on the current passing through the wire, or on the 
ampere-turns. 

Action of the Electric Generator. — The action of a generator 
depends on the fact that when a wire or other conductor of elec- 
tricity is moved between the poles of a magnet, electrical pressure 
is induced in the conductor. In the simple electric generator, an 
armature consisting of only one coil of wire is rotated between 
the north and south poles of a magnet. The ends of the coil are 
connected to two insulated rings mounted on a shaft which gives 
rotary motion to the coil. If two brushes are allowed to bear on 



GENERATORS, ELECTRIC MOTORS, ETC. 249 

the two rings and are connected to a measuring instrument, it will 
be noticed that the current will flow in one direction during half 
of a revolution and in the other direction during the next half of a 
revolution. If the readings of the instrument are recorded graph- 
ically, a curve like Fig. 242 will be obtained. In this curve the 
horizontal distances represent the angles turned, while in the 
vertical distances are recorded values of electrical pressure in volts 
which cause a corresponding flow of electric current at the various 




Fig. 242. — Alternating current. 

angular positions. It will be noticed that the current starts at 
zero, and increases to a maximum during one-quarter turn. At 
the half turn it is zero again. After half of a revolution the 
direction of the current reverses, attains a negative maximum at 
three-quarters of a turn and then is again diminished to zero. 

Direct and Alternating Currents. — The action of the simple 
generator, explained in the last section, produces an alternating 
current, which varies from a maximum to a minimum, first 
in one direction and then in the other. In the actual electric 
generator there are many conductors in the armature and several 
sets of poles, so that as the armature revolves, the current reverses 
its direction many times a second. For long-distance electric 
transmission this type of electric current usually is used, as 
alternating currents can be generated at very high voltage, and 
these voltages can be increased or decreased at pleasure by means 
of simple instruments called transformers. There are, however, 
certain uses to which the alternating form of electric current 
cannot be put. One case was mentioned in connection with the 
charging of storage batteries, where a direct current must be used, 
the chemical action necessary in a storage battery being an 
impossibility with an alternating current. 

Direct current is generated in a generator by the addition of a 



250 



FARM MOTORS 



commutator shown in Fig. 243, which consists of a set of seg- 
ments insulated from each other and from the armature shaft, and 
which rectify the current by shifting the position of the brushes 
with respect to the armature coils. The principle of the commu- 
tator can be seen from Fig. 244. R is 
a split ring to the two segments of 
which are fastened the two ends of the 
coil, explained in connection with the 
working of the simple dynamo. The 
two brushes BC are connected to two 
wires carrying off the current to the 
external circuit. As the coil of the 
simple armature gets into the vertical 
position between the poles of the 
magnet each brush changes from the 
segment with which it was in contact 
to the other, so that the effect is just 
the same as if the brushes were inter- 
changed, and the current generated 
during the second half of the revolution 
flows in the same direction round the 
external circuit as the preceding current 
did. The current, although generated in the reverse direction, 
enters the external circuit at the other end, and the result is a 
unidirectional current. This is changed into a 
direct current by the employment of an armature 
with a large number of coils and a commutator 
of many segments. 

Principal Parts of Generators and Motors. 
— The principal parts of all dynamo — electric 
machinery, whether they be generators of elec- 
tricity or motors driven by electric current, are: 

1. A magnetic field, commonly called a field, 
whose function it is to furnish magnetic lines. In the earlier 
machines this consisted of a two-pole magnet but the modern 
generators and motors are provided with four or more poles. The 
reason for this is that a more compact machine can be produced. 
A generator whose field consists of a two-pole magnet is called 
a bipolar generator, while one with a magnet consisting of four 
or more poles is called a multipolar generator. 




Fig. 243. — Commutator. 




Fig. 244.— 
Principle of the 
commutator. 



GENERATORS, ELECTRIC MOTORS, ETC. 251 



2. An armature which is made up of insulated windings of 
copper wire on an iron core. The function of the armature is to 
cut the magnetic lines of force furnished by the field. In all 
direct-current machines the field is the stationary part while the 
armature revolves. In alternating-current machines, the field 
is the revolving part in all but the very small machines. 

3.« A device which collects or delivers current to the armature, 
depending on whether the machine is a generator or a motor. 
In the case of alternating-current generators and motors this is 
accomplished by brushes pressing on collector rings, if the arma- 
ture is the revolving element. In larger alternating-current 




Fig. 245. — Parts of dynamo-electric machinery. 

machines where the armature is the stationary part, the current 
is taken away from or delivered to the windings by leads entering 
the frame of the dynamo or motor. When dealing with direct- 
current machines, current is delivered to or taken away from the 
armature by brushes pressing on a commutator whose function, 
as explained in the earlier part of this chapter, is also to change 
the alternating current into direct current. 

4. A shaft passing through the revolving part, which is con- 
nected to the engine furnishing power in the case of the generator 
and to the machine to be driven in the case of the electric motor. 

5. A frame, usually made of cast iron, whose function it is 
to support the bearings in which the shaft of the generator or 
motor revolves. 



252 FARM MOTORS 

The various parts of a direct-current generator or motor are 
illustrated in Fig. 245. The field and armature of an alternating- 
current generator are illustrated in Figs. 246 and 247 respectively. 

Classification of Generators and Motors. — The first broad 
classification is into direct- and alternating-current generators 
and motors. 

Direct-current generators and motors are divided into three 
classes depending on the type of field winding as series-wound, 
shunt-wound, and compound-wound. For simplicity these 
three types are represented as bipolar machines in Figs. 248, 
249, and 250. 

Series-wound Generators. — In the series-wound dynamo, illus- 
trated by Fig. 248, one end of the field winding is connected to 
the positive brush and the other to the external circuit. The 
action of the series-wound machines depends on the fact that the 
soft iron poles retain sufficient magnetism to send out a current 
to the external circuit when the armature is rotated. The entire 
current passing through the field, the electromagnet of the field 
increases in strength as the current developed by the generator 
becomes greater. Series-wound generators are used mainly to 
supply electricity to direct-current arc lamps. 

Series-wound Motors. — The series-wound motor has a winding 
similar to that of the series-wound generator. In fact, it is 
difficult to tell the difference between any direct-current 
motor and generator, the electrical features being the same. A 
series- wound generator when operated as a motor will run in re- 
verse direction. The series-wound motor is used for work where 
hand control can be used as in the operation of hoists, cranes, 
and for the propulsion of electric cars. A series-wound motor can 
be started at full-load and should never be used where there is a 
possibility for the load to be removed suddenly. A series-wound 
motor will "run away"; that is, its speed will increase to such an 
extent that it may be destroyed by centrifugal force, if the load 
is removed. For this reason it is not safe to use belt drives with 
series-wound motors. A series motor is illustrated in Fig. 249. 

Shunt-wound Generators. — The principle of a shunt-wound 
generator is illustrated in Fig. 249. The field winding consists 
of a great number of turns of very fine wire. Both ends of the 
field winding are connected to the brushes of the generator. 



GENERATORS, ELECTRIC MOTORS, ETC. 253 




Fig. 246. — Field of alternating-current generator. 




Fig. 247. — Armature of alternating-current generator. 



A/ 

Armature 





S 

■& 7 Brush 



N 
Armafur 





Fig. 248.— Series- Fig. 249.— Shunt-wound Fig. 250.— Compound- 
wound dynamo. dynamo. wound dynamo. 



254 FARM MOTORS 

Since the field winding is very small in comparison with the line 
wire, only a small part of the current flows around the field coils. 
This type of generator is used for charging storage batteries. A 
shunt-wound generator will supply constant voltage provided the 
load does not vary much. 

Shunt-wound Motors. — The shunt-wound motor has the same 
type of winding as the shunt-wound generator. Shunt-wound 
motors are used for all kinds of work where fairly constant speed 
is desired. A well-designed shunt-wound motor will not vary 
much in speed with a variable load. In starting a shunt-wound 
motor it is necessary to put considerable resistance in series with 
the field of the motor. This is due to the fact that the resistance 
of the armature of a shunt-wound motor is very low. If a volt- 
age of from 110 to 220 volts is allowed to pass through an arma- 
ture of low resistance, an enormous current would flow through 
the armature in starting, which would result in injury to the 
armature coils, and also to the commutator by excessive spark- 
ing. By putting a resistance in series with the armature the 
current which is allowed to pass through it is decreased. Then, 
as the motor begins to speed up, the armature turning between 
poles of a magnet, produces a generator action which sends an 
electrical pressure in opposition to that which is sent in from the 
mains. This tends to reduce the current passing through the 
armature to a safe limit. In connection with this, it must be 
remembered, that weakening the field of a shunt-wound motor, 
reduces the above-mentioned generator action, and speeds up the 
motor. A break in the field connection of a shunt-wound motor, 
while it is in operation, may result in considerable damage by 
overspeeding. 

Compound-wound Generators. — The compound-wound gen- 
erator is used extensively for the generation of current for all 
purposes, including that for light, power and street-car propul- 
sion. The voltage of this type of machine is automatically 
regulated by a combination of a shunt and series winding. This 
type of winding is illustrated in Fig. 250. A large portion of the 
field is wound with many turns of fine insulated wire, which must 
produce a field of sufficient strength to generate the rated volt- 
age of the generator when no load is placed on it. A series wind- 
ing of several turns of heavy wire is wound over the shunt wind- 



GENERATORS, ELECTRIC MOTORS, ETC. 255 

ing. This series winding adds sufficient strength to the field so as 
to develop the standard voltage at the maximum load of the 
generator. In some compound-wound generators, the series 
winding is arranged to increase the voltage slightly as the load 
increases, and to compensate for loss in voltage during trans- 
mission. 

Compound -wound Motors. — The compound-wound motor has 
a series and shunt winding like the compound-wound generator. 
It is used mainly for the driving of machines where very close 
speed regulation is essential, such as printing presses, machine 
tools, and looms. 

Various Types of Motors Compared. — For most purposes, 
the shunt-wound motor is very satisfactory, and, being much 
cheaper than the compound-wound motor, it is used for the driv- 
ing of all kinds of machinery which can be started at no-load. 
If motors are to be used for pumping, the series-wound or com- 
pound-wound motor should be selected, unless a clutch can be 
inserted between the motor and the pump. 




<><><><>(><> : 



— B 

Fig. 251. — Parallel system of distribution. 

Distribution of Electric Current. — Electricity may be dis- 
tributed as direct or as alternating current. Direct current 
usually is used for short-distance distribution, the most common 
voltages being 110 and 220 volts. If the furthest point of the 
distributing system is a mile or further from the dynamo it is 
well to use alternating currents in order to reduce the cost of 
wire. Alternating currents are used in voltages of 1,100, 2,200, 
4,400, 6,600, and higher. 

When using direct currents the parallel system of distribution 
is most common. The principle of this system is illustrated in 
Fig. 251. The feeders A and B lead from the generator D to the 
switchboard. The mains EF and GH connect the feeders with 
the branches which supply current for lamps, motors, etc. 

In another system of direct-current distribution, the series 



256 



FARM MOTORS 



shown in Fig. 252, the lamps are connected in series with the 
generator D. This system is very seldom used at the present 
time, and then only for supplying current to direct-current 
street arc lamps. 

+- — o — o — o 




Fig. 252. — Series S3^stem of distribution. 

Electric Meters. — The four most important quantities which 
must be known are : current, voltage or electrical pressure, resist- 
ance and power. Then most switchboards are also provided 
with ground detectors for the purpose of telling when the circuit 
is grounded. 





Fig. 253. — Ammeter. 



Fig. 254.— Voltmeter. 



Electric current is measured by an instrument called an amme- 
ter, and illustrated by Fig. 253. This instrument usually con- 
sists of a coil of wire between the poles of a permanent magnet. 
The current to be measured is sent through the coil, this produc- 
ing a movement of the coil which is recorded by a needle on a 
graduated scale. 

A voltmeter, illustrated in Fig. 254, is used for measuring elec- 
tric pressure. This instrument differs from the ammeter in that 
a resistance is placed in series with the coil, otherwise the volt- 
meter and ammeter for the measurement of direct current are 
alike. 



GENERATORS, ELECTRIC MOTORS, ETC. 257 

For the measurement of voltage and current of batteries a 
battery meter illustrated in Fig. 255 is used. 

The method of connecting an ammeter M and a voltmeter V 
to a circuit is shown in Fig. 256. AB and CD are the two wires 
of the circuit. 

Resistance can be measured by using a voltmeter and an 
ammeter together. The ammeter is connected in series with 
the resistance, while the voltmeter is connected to the terminals. 
The resistance can then be calculated by Ohm's law, explained 




n 



52 



— D 



Fig. 255. — Battery meter. 



Fig. 256. — Method of connecting ammeter 
and voltmeter. 



in the beginning of this chapter. If I is the ammeter reading 
and E is the voltmeter reading the resistance is 

E 
I 



R = 



An instrument which measures the electrical power of a cir- 
cuit is called a wattmeter. Since the power of a direct-current 
circuit is the product of the current flowing through the circuit by 
the voltage between the terminals, the power can be obtained 
by taking the product of the voltmeter and ammeter readings of 
any circuit. In alternating-current circuits this product of the 
voltmeter and ammeter readings does not give the true electric 
power of the circuit and a wattmeter must be used. Direct- and 
alternating-current wattmeters are illustrated in Figs. 257 
and 258 respectively. 

Fuses and Circuit-breakers. — The function of fuses and of 
circuit-breakers is to protect electric machines, appliances and 

17 



258 



FARM MOTORS 




Fig. 257. — Direct-current wattmeter. 




Fig. 258. — Alternating-current wattmeter. 



GENERATORS, ELECTRIC MOTORS, ETC. 259 

wires from being traversed by currents above their safe carrying 
capacities. 

Fuses are made of an alloy of lead and zinc. For temporary 
connections fuse wire is used. A better method is to solder the 




•iiiniiiiiiiiii'ii '■;,//! i' LLUii. 




Fig. 259.— Fuse. 





Fig. 260. — Edison plug cutout and fuse. 




Fig. 261. — Enclosed-type fuse and fuse-block. 





Fig. 262. — Circuit breakers. 

wire to copper terminals as shown in Fig. 259. The Edison plug 
cutout and fuse, illustrated in Fig. 260, is very convenient. 
Another form, the inclosed type of fuse, is shown in Fig. 261. 
Due to the uncertainty and unreliability of fuses, circuit- 



260 



FARM MOTORS 



breakers are employed for the protection of lines carrying heavy 
currents. 

Several forms of circuit-breakers are illustrated in Fig. 262. A 
circuit-breaker is a switch which opens automatically where the 
current passing through it is greater than that for which it is 
set. Circuit-breakers are made to open either one or both sides 
of the circuit and are named accordingly single-pole and double- 
pole circuit- breakers respectively. 

Switches and Rheostats. — The functions of a switch and rheo- 
stat in an electrical circuit are analogous to that of a valve in a 




Fig. 263.— Switches. 



steam or water line. The switch opens or closes the circuit while 
the rheostat regulates the strength of the current passing. 

For controlling the flow of small currents in connection with 
the illumination of rooms, some form of snap switch or push- 
button switch is employed. These switches can be made to 
control the current from two, three, or four different places. A 
special form of push-button or snap switch, called the electrolier 
switch, can be used for turning on part or all of the lamps on an 
electric-light chandelier. Thus in the case of a four-light chande- 
lier, this type of switch can be wired so that the burning of one, 
two, three, or all of the lamps can be controlled from the wall of the 



GENERATORS, ELECTRIC MOTORS, ETC. 



261 



room. Several forms of snap and push-button switches are 
illustrated in Fig. 263. 

For currents above 25 amp. a knife switch should be em- 
ployed. This type of switch has a contact-making piece of a 
shape somewhat like a knife. A single-pole knife switch opens 




Fig. 264. — Knife switches. 

only one side of a circuit, a double-pole two sides, etc. Double- 
throw switches are used when one of two circuits has to be con- 
trolled at a time. Several forms of knife switches are illus- 
trated in Fig. 264. 




Fig. 265.— Rheostats. 



A rheostat for controlling the strength of electric current is 
illustrated in Fig. 265. The fundamental parts of a rheostat 
are : coils of iron wire to absorb electric current, metallic points 
connecting the various coils to the outside, and an arm which is 
moved over the various points. 



262 



FARM MOTORS 



Method of Connecting Motors. — The method of connecting 
a shunt motor and its starting box to the circuit is illustrated 
in Fig. 266. A and B are the two leads which bring the current 
from the mains (connected to a generator) through the fuses P, 
R and to the switch S. One terminal of the switch L is connected 
to the field F and to the armature G of the motor. The other 



<? 



& 




0! 



i 



» 

i 
i 
i 
i 
i 
» 
» 
» 

6[C 




f 







<J 


¥ 111 










1 


' *■ 
















' B§ 









Fig. 266. — Method of connecting 
motors. 



Fig. 267. — Motor-driven pump. 



terminal K leads to the starting box. The handle H of the start- 
ing box is connected with the terminal E, which is attached to the 
armature of the motor. The other terminal D of the starting 
box is connected with the field of the motor F. 

When the motor is to be started, the switch S is closed and the 
handle H is on the contact point 1. The handle H is then 
moved slowly to the right. When the handle H is on the last 
contact point, it is held in position by the magnet M. To stop 



GENERATORS, ELECTRIC MOTORS, ETC. 263 

the motor, the switch S is opened. The magnet M, losing its 
magnetism, allows a spring to bring back the arm H to the start- 
ing point. 

The Electric Motor on the Farm. — The electric motor is well- 
suited for most farm work which is accomplished by the small 




Fig. 268. — Motor-driven washing machine. 



stationary gasoline engine. It is not as portable in any but the 
very small sizes, but possesses other advantages for certain 
uses. A small electric motor requires no special foundation and 
may be placed on the floor, on a truck, or may be fastened to 
the wall or ceiling, is easily started and requires less care than 
the gasoline engine. The cleanliness of the electric motor and 



264 



FARM MOTORS 



the absence of offensive fumes make it more desirable for use 
in the house, the dairy and the barn. 

Some of the uses of the electric motor in the home are illus- 
trated in Figs. 267 to 269. The house pump driven by a motor of 
Y§ hp. is shown in Fig. 267. Another electric motor of }{q hp. 
drives a washing machine illustrated in Fig. 268. Still a smaller 




Fig. 269. — Motor-driven sewing machine. 

motor is shown connected to a sewing machine in Fig. 269. Other 
uses to which the electric motor can be put in the farm house- 
hold may be mentioned : the driving of fans during hot weather, 
of vacuum cleaners, of ice-cream freezers, of cream separators, 
of churns, of milking machines and of grindstones. An electric 
motor can also be used for the shelling and grinding of feed and 
for the many operations in the farm shop. 

For outdoor use and for the heavier farming operations the 
electric motor is not as suitable as the gasoline engine. 



GENERATORS, ELECTRIC MOTORS, ETC. 265 

The Farm Electric -light Plant. — For farms of the average 
size, which do not have the advantages of cheap power from 
a nearby transmission system, private electric-lighting plants 
driven by gasoline engines are becoming quite common. 

When an electric-light plant is to supply current for lighting 
only, the complete installation, including the wiring of an average 
eight-room house and barn, will vary from $350 to $750. If the 




Fig. 270. — Farm electric-light plant. 

plant is to supply current for motors as well as for lights the first 
cost will be from $1,200 up, depending on the size of motors 
used. The cost of operating a plant for lighting only will usually 
be about $15 a year. The cost of operating plants which supply 
electricity for power will depend on the size of motors and on the 
amount of work done. 

The essential parts of a private electric-light plant are: 

1. A gasoline engine and an electric generator. 

2. A set of storage batteries for storing the electricity to be 
used when wanted and which supplies a steady light whether 
the engine is running or not. 



266 



FARM MOTORS 



3. A switchboard with an ammeter, a voltmeter, fuses and 
switches to control the operation of the dynamo and of the 
storage battery. 

4. Wires from the switchboard to the house, barn and other 
places where electricity is to be used. 

5. Wiring of the house, barn, etc. 

In Fig. 270 is illustrated a farm electric-light plant. 



OIL HOLE : ^*m 

EXHAUST VAin \ A ■ 


B*^ ^ — - 


OIL -LESS BEABiNG : 
INTAKE VALVE ; : 


LIGHT- asm [: PGWfR W1815 _ ^|§ "^'~-^OlH 


MkL - 


CYLINDER HEAD 


PUSH ROD A OJU&TMENT___^__J| 

ughtan o po w lr s vv i i c ii_^SPi!ji| 

STOPPING SWITCH ._jMBpHB 

SPARK PLUG ZjHOI 

STARTING SWITCH^ 


1 " ""iv-"-* 


: - 9' — ~ 


MIX8N6 VALVE 

CHECH VALVE 

DRAFT TUBE 






. w.^^ 


_GASOUNrTANH 


BATTERY GAUGE 1S3BI | 




' ■ •""^■^^■^^^ 


■__ - CYLINDER 

ALUMINUM PISTON 








!■ ^HT--~ 


OIL GROOVE S 

_ FLV WHEEL 

CONNECTING ROD 


SGWTIQN C0U. m 


- — ; yiifii Jim 


«p^ j ;::;:. - ■ 






" 1 


m* >H4JT BALANCE WEIGHTS 


VAtVE Uf TING CAM 


':" »* .Lb^SJ "■■ 


VfATT ROUES BEARING 


BRUSH _; A 

COHHUTATQfi J 




■rt 5-'... 1 




GENERATOR CBTOjj 
ARMATURE ", j 

giTjffiOWWfl^AR: 




^"*" ^^1h 


- 


OIL THROWER 

, CvNNECTlNS ROD BEARING 


~ ^UpM 


: RELD CPU 




-^■r"* f ^;*" r * j 


CRANK CASE 


• ^ U$ZJ7~2Z- -&*:WKSffl 


- : 


"3B 


»SBBi4a*-' i:) ,J| 


BASE 



Fig. 271. — Engine and generator for farm electric-light plant. 

The use of the private electric-light plant for farms of average 
size was out of the question until quite recently on account of the 
great cost of the storage battery. With the ordinary carbon 
lamps operating at 110 volts, about 60 storage cells were required 
to maintain the correct voltage when the engine was not running. 
The development of the tungsten lamp, which operates satis- 
factory at about 30 volts, necessitates the use of a battery of only 
17 cells, and has the added advantage of greater safety from 



GENERATORS, ELECTRIC MOTORS, ETC. 267 

short-circuits. Then the tungsten lamp consumes only about 
one-third of the electric energy required by the carbon lamp of 
the same candlepower. 

Installation of Electric Motors and Generators. — A dry, cool 
and clean place, free from dust, should be chosen for the location 
of an electric machine. If the surrounding air is warm, the tem- 
perature of the various parts is likely to rise to a sufficient degree 
to endanger armature, or field, or both. 

If a motor has to be located in a dusty place, or in connection 




Fig. 272. — Enclosed-type motor. 

with farming operations where particles of feed or trash may lodge 
on the motor, an inclosed type like the one shown in Fig. 272 
should be selected. 

In locating motors or generators care should be taken to pro- 
vide easy access to all parts. Also sufficient distance must be 
allowed between the pulley centers of the driver and driven. 

A substantial foundation of timber, brick, or concrete should 
be provided for all motors and dynamos above 25 hp. Small 
machines can be fastened to the floor and require no special 
foundation. 

If an electric machine has been exposed to changes of climate, 



268 FARM MOTORS 

it should be kept in a warm, dry place for several days, as the 
insulation always absorbs dampness which can be only slowly 
dried out. 

Small machines usually are shipped complete and ready to 
run. Large motors and generators usually are shipped in boxes, 
" knocked down," as this reduces freight charges. 

In assembling parts, all connections and parts should be wiped 
perfectly clean and free from grit. The bearing sleeves and oil 
rings should be placed in position on the shaft before the armature 
is lowered in place. 

The bearings should be filled with a good grade of thin lubri- 
cating oil, care being taken not to fill the oil cellars so they will 
overflow. 

In clamping the brushes in place, they should be adjusted so 
that the pressure on the commutator is about 1J^ lb. 

The brushes are fitted to the commutator by passing beneath 
them No. sandpaper, the rough side against the brush and the 
smooth side held down closely against the surface of the commu- 
tator. The sandpaper should be moved in the direction of rota- 
tion of the armature, and on drawing it back for the next cut, 
the brush should be raised so as to free it from the sandpaper. 
It is then lowered and repeated until a perfect fit is obtained be- 
tween the brush and commutator. 

Starting and Stopping Motors. — Before starting a machine 
for the first time, care must be taken that all set screws and nuts 
are tight and that the oiling system works properly. The arma- 
ture is then turned by hand to see that it is free and does not rub 
or bind at any point. The wiring should be carefully gone over 
and all terminals screwed down tightly. When everything is in 
good condition, the switch is closed, but before doing this one 
must make certain that the starting-box handle is in the "off" 
position. After the switch is closed, the handle on the rheo- 
stat is moved, gradually cutting out the resistance as the motor 
speeds up. 

It is well to run a new motor for a time before putting on the load. 

In stopping a motor, pull the switch and the handle of the 
starting rheostat should fly back to the "off" position. 

Starting and Stopping Generators. — The general rules in regard 
to starting an electric machine are alike for the generator and 



GENERATORS, ELECTRIC MOTORS, ETC. 269 

motor. When the generator is ready to be started, place the 
driving belt on the pulley of the armature shaft and start the 
engine driving the generator, bringing the machine up to speed 
very slowly. 

Generators usually are tested before they leave the factory. 
As a rule, generators will retain sufficient magnetism in their 
fields so they can be started. Sometimes a generator loses its 
field magnetism on the way from the factory to its destination. 
The fields can be magnetized by current from a battery or from 
another dynamo. 

If a generator is supplying incandescent lamps, the main switch 
should not be closed until the machine is developing the correct 
voltage. 

In stopping a generator, the load is first removed and the 
engine driving the generator is then stopped in the usual manner. 

Care of Motors and Generators. — It is very important to keep 
electric machines clean and all insulation free from dust and gritty 
substances. 

The commutator should be kept clean and allowed to assume 
a glaze while running. Oil should not be used on commutators, 
as it chars under the brushes, forming a film between commutator 
bars which may cause a short-circuit. 

The commutator brushes should be kept in good shape. They 
should be removed frequently for inspection and cleaning, and 
if necessary should be filed. To remove grease or dirt the brushes 
should be soaked in gasoline. 

If the brushes are not properly trimmed or are in poor condi- 
tion the commutator will present a bright coppery appearance 
and will be found rough when felt by hand. If in very poor 
condition, the commutator may have to be turned down. 

Sparking at commutators usually will occur if brushes are 
improperly set, commutator is rough, machine is overloaded, 
short-circuited or grounded. 

Heating of armatures may be caused by the short-circuiting 
of some of the armature coils or by too great a load. A short- 
circuited armature coil usually can be detected by its high tem- 
perature. If a greater part of the coils are short-circuited the 
determination becomes more difficult and sensitive instruments 
have to be used. 



270 FARM MOTORS 

A hot bearing also will cause the heating of the armature, and 
this usually can be detected and remedied. 

Problems: Chapter X 

1. What is meant by the following electrical terms: voltage, amperes, 
kilowatts, electrical horsepower, ohms? 

2. Calculate the current consumed by a 25-watt tungsten-filament lamp, 
which is operated on a 110-volt circuit. 

3. State and explain the application of Ohm's law. 

4. How does the current consumed by the tungsten-filament lamp 
compare with that consumed by the carbon-filament lamp of the same 
candlepower? 

5. Explain the Brown and Sharpe wire gage and calculate the size of rub- 
ber-covered wire required to carry a current of 10 amp. Neglect transmis- 
sion losses. 

6. Calculate the power of a gasoline engine required to drive an electrical 
generator of 3 kw. capacity. 

7. Calculate the horsepower of a gasoline engine required to supply twelve 
40-watt tungsten-filament lamps and four 16-cp. carbon-filament lamps. 
Allow 25 per cent, for losses. 

8. If an arc lamp consumes 5 amp. at 110 volts, calculate its resistance. 

9. What is a primary battery? a storage battery? 

10. Explain the composition of the dry cell. In which respects does the 
construction of the dry battery differ from the ordinary wet battery? 

11. What are the fundamental parts of a lead storage battery? 

12. Give directions for testing a storage battery. 

13. How distinguish the positive and negative plates of a lead storage 
battery ? 

14. How are storage batteries rated? 

15. In which respects does the Edison battery differ from the lead storage 
battery? 

16. What is the voltage of a storage battery of 32 Edison cells connected in 
series ? How much greater would the voltage of this battery be if made up of 
lead cells? 

17. How should a battery of six dry cells be connected to give the greatest 
voltage? Calculate the approximate voltage of the battery. 

18. How should storage batteries be connected to give the greatest voltage 
and as much current as possible? Illustrate by sketch. 

19. When should the multiple system of battery connection be used? 

20. The reading of an ammeter connected in series with a coil is 18 amp. 
If the voltage between the terminals is 7 volts, calculate resistance of coil. 

21. Calculate the current which will flow through a resistance of 440 ohms, 
the voltage between terminals being 110. 

22. Can alternating current be measured by direct-current instruments? 
Give reasons for your answer. 



GENERATORS, ELECTRIC MOTORS, ETC. 271 

23. Give clear abstract of Bulletin No. 1 of the Kansas State Agricultural 
College Engineering Experiment Station and of Bulletin No. 25 of the Iowa 
State College Engineering Experiment Station. These bulletins deal with 
illumination for farm homes. 

24. Give directions for installing electric motors. 

25. Give directions for starting a shunt-wound direct-current motor. 



CHAPTER XI 
ANIMAL MOTORS 

Animals used in the United States as farm motors include 
mainly horses, mules, and oxen. Sheep, dogs, goats, camels, 
water-buffalos, elephants, reindeers, and caribous are used to a 
limited extent in other countries. The power developed by 
horses and mules on American farms exceeds that generated by 
all other forms of farm motors, animal as well as mechanical. 

The Horse. — Of all animal motors the horse is the most impor- 
tant for farm use. The horse is intelligent, willing, a fast walker 
as compared with other draft animals, and self-reproducing. 
Large-sized hoofs make it possible for horses to be used on 
comparatively soft ground. 

Selection of a Draft Horse. — Dr. H. J. Waters, in his book, 
"The Essentials of Agriculture," l gives the following rules for 
judging draft horses: 

"Size and weight are determining factors in the classification of 
draft horses. To belong to this class a horse should weigh 1,600 lb. 
or more and should be at least 15.2 hands high. Value increases with 
size, other things being equal. 

"The draft horse should be deep, wide, and compact of body, and 
should carry his weight uniformly. The top line should be strong and 
short, while the under line should be long and straight. Quality is an 
essential of good service. It is indicated by fine hair; clean, strong 
joints clean, flat legs; and tough, firm feet. The head should be 
clearly defined and bony in appearance, with good width of forehead. 

"The head should be proportionate to the body, neither too large 
nor too small, with clean muzzle, medium ear, bright eye, broad fore- 
head, and a clean throatlatch. A thick throatlatch usually indicates 
'poor wind.' The neck should be of medium length, with a slight crest, 
and should be well-muscled. The shoulders should be long and slop- 
ing, in order to give breaking surface for the collar and to lessen the 
concussion of hard streets. Good muscular development of arm and 
forearm is essential. The withers should be of medium height. A 
back with close coupling and with a long, heavy-muscled croup is a 

1 H. J. Waters, "The Essentials of Agriculture," Ginn & Co., 1915. 

272 



ANIMAL MOTORS 273 

conformation representing the greatest strength. Long, well-sprung 
ribs with a deep and well-filled rear flank make room for a well-developed 
digestive apparatus and strong vital organs. Muscular development 
of the hind quarters is essential. The draft horse should stand squarely 
on its legs. The legs should be clean, with bone of good size and with 
strong joints. The pastern should be sloping, and the hocks should 
be large and of regular shape. 

"Constitution is indicated by a deep, broad chest, together with a 
well-sprung rib, a deep body, bright eyes, and great energy. 

"The action of draft horses is important. The stride at the walk 
and trot should be long, straight, and regular. Correct conformation 
gives elasticitjr to the walk and the trot in all horses. Reasonable 
grace and style of carriage are demanded." 

When pulling a heavy load there is a tendency for the horse 
to lift his front feet off the ground. This tendency decreases 
as the weight of the horse increases. The distribution of weight 
is also an important consideration. 

The hock muscles should receive careful attention, as such 
muscles, when deficient in strength, limit the ability of a horse to 
pull a load. The wider the hock, the more leverage the muscle 
will have. 

The other essentials for a draft horse are broad muscular 
breast, heavy muscles of arm and forearm, large well-supported 
knees, short cannons, strong fetlocks and pasterns, and large, 
sound feet. 

Capacity and Power of Draft Animals. — The average draft 
horse can exert from day to day a pull from one-eighth to one- 
tenth of his weight for about 10 hr. a day, if walking at the nor- 
mal rate of about 2J^ miles per hour. The skeleton and muscular 
development of the horse is such that he is adapted to pulling 
loads. A horse is capable of pulling a load several times his own 
weight, while his carrying capacity is only a fraction of the weight 
of his body. 

A draft horse weighing 1,600 lb., when pulling a load one- 
tenth of his weight at the rate, of 2 miles per hour, will develop : 
TT Draft X distance traveled per minute 
Horsepower = - 33,000 

In the case of the above problem, the draft of the horse is 

( ' J = 160 lb., the distance traveled is 2 miles per hour or 

18 



274 FARM MOTORS 

(2 X 5,280) = 10,560 ft. per hour, or (^p) - 176 ft. per min- 

^, , ... 160 lb. X 176 ft. per minute 
ute. The horsepower developed = QQ 

= 0.853. 

The weight of the ordinary draft horse usually is less than 
1,600 lb. and the average power developed by a draft horse 
when worked at normal rate is about % hp. Horses can develop 
power much in excess of the normal amount for short periods of 
time. Tests have demonstrated that for very short periods of 
time a good draft horse can develop as much as 4 or 5 hp. This 
ability of the horse to stand overloads may be advantageous in 
emergencies, but must not be taken advantage of too frequently. 

Power being the rate of doing work, an increase in the speed 
of a horse should be accompanied by a reduction in the load to be 
carried by the animal. On the other hand, if the working day is 
reduced from 10 to 4 or 5 hr., the load may be increased. Thus 
the capacity for tractive effort decreases as the speed and the 
time increase. 

The power developed by a horse when trotting or galloping 
is decreased by the fact that the heart action is greatly increased 
and heat is lost by the evaporation of water through the skin and 
lungs, thus leaving only a small portion of the energy in the fuel 
available for work; much energy is used up non-productively 
also in the horse's raising his own body in galloping. 

It is not advisable to work horses of unequal size and weight 
together. Horses should be chosen similar in temperament, 
type, and weight. 

It is not desirable to have horses work too close together or 
under conditions which may result in the draft animal fretting. 
Fretting uses up energy which should be made available for useful 
work. 

Hip straps, if too short, will reduce the capacity of a horse for 
work, as the animal with short hip straps carries part of the load. 

Other factors which influence the power developed by draft 
animals are the grip on the surface of the road and the angle 
of trace. The angle of trace is the angle between the tugs and 
the surface of the ground. This angle should be considered with 
reference to the comfort of the horse and the least draft. 



ANIMAL MOTORS 275 

Selection of Feed for the Horse. — The selection of proper feed 
is as important to the successful maintenance and use of a horse 
as is the securing of proper fuel and of good lubricating oil for 
operating a steam traction engine or an oil engine. 

The feed supplied to the animal must contain sufficient 
nutritive material for building up the bodies of young animals, 
as in growth and for repairing the tissues of the bodies of animals 
of all ages which are constantly being worn out by work or other 
exercise. The feed must also, in addition to accomplishing these 
purposes, be capable of developing energy necessary for carrying 
on the complex processes within the animal body, as well as the 
energy for performing external work as a motor. The horse is 
fed properly, if constant body weight is maintained while doing 
normal work. Loss in weight means insufficient or improperly 
selected food or overwork, while a gain in weight indicates unnec- 
essary expenditure of food, unless it be to overcome the effect 
of temporary overwork. In general, stationary body weight is a 
safe guide in the feeding of work horses, but in practice it fre- 
quently happens that horses are worked so hard for short periods, 
as during plowing and seeding season, or harvest season, that it is 
not possible to supply enough nutrients during such period to 
maintain a constant body weight, or to prevent the horse from 
losing weight. Such a period usually is followed by one of com- 
parative idleness, as in the winter, when the horse is fed liberally 
enough to store fat on its body to be used as a source of energy 
during the rush season that is to follow. 

Fat is the most concentrated form of animal food known and 
contains about 2% times as much energy per unit of weight as 
the starches and sugars. 

When feed is abundantly nutritious, animals store up fat 
with which to protect themselves against the cold, or to supply 
the energy to enable them to travel to new sources of nourish- 
ment when the old supply fails, or to new sources of water. 

The feed supplied for building up and for repairing the body 
and tissue must contain certain nutrients. These nutrients are 
protein, mineral matter, carbohydrates, and water. 

Protein is the term supplied to a group of organic substances 
of which casein of milk, white of egg, and the gluten of wheat are 



276 FARM MOTORS 

examples. The protein forms the basis of the living tissues, is a 
source of growth of animals, and is the material used principally in 
repairing the waste of the body. Protein may be also the source 
of energy, but there are many cheaper and more efficient sources 
of energy, and protein is too costly to be used principally for this 
purpose. There is, however, no substitute for protein as a source 
of growth, or as a means of repairing the worn body tissues. 

Mineral matter, or ash, is the inorganic material present in 
different feeding stuffs. The mineral matter in the food supplies 
material principally for the formation of the skeleton, hoof, and 
horn, but is necessary also for the production of soft tissues. 
Most feeds contain plenty of mineral matter to satisfy all the 
requirements of work animals. 

The carbohydrates are the principal source of energy and are 
chiefly used in building up the body and fat, which is simply 
stored energy. Familiar forms of carbohydrates are the sugars, 
starches, oils and fats, and woody fibers. 

The animal body requires protein, mineral matter, and carbo- 
hydrates in definite proportions, depending upon the kind of 
animal, its age, and what the animal is doing. A young, active 
colt, for example, requires a more generous supply of all of these 
materials in proportion to its body weight than a mature horse. 
That is ideal, because the colt is growing rapidly and requires for 
the support of this process much protein and mineral matter. It 
is also active and requires considerable fuel, or carbohydrates, 
to supply the energy expended. A horse that is hard at work 
will require more food and a greater proportion of protein and 
mineral matter than will one that is idle, because there is greater 
expenditure of energy, and because activity causes a greater wear 
upon the body tissue. 1 

The Mule. — The mule is tougher and hardier than the horse, 
is less subject to disease or inflammation from slight injuries, 
may be handled by less intelligent farm labor, and is better able 
to take care of itself than is the horse. 

The mule is used very largely as a work animal in the Southern 
States. 

The Ox. — The ox has much endurance and is not excitable, 

1 The composition of various feeds can be found in Farmer's Bulletin No. 
170 of the United States Department of Agriculture. 



ANIMAL MOTORS 277 

but is slow and unintelligent, and has little spirit. Oxen are 
seldom used at the present time, but their use is increasing in some 
regions, because of the steadily increasing cost of horses. 

Cost of Animal Power. — The cost of maintaining a horse, 
when there are taken into consideration feed, labor in caring, 
depreciation of horse, depreciation of harness, shoeing, shelter 
and interest on the investment, varies from $100 to $150 per 
year. 

The cost of feed per horsepower per hour with animal motors 
has been estimated at about 6 cts. The total cost of power, with 
animal power, per horsepower per hour when considering the to- 
tal cost of maintaining the animal has been estimated at about 
12 cts. 

Problems: Chapter XI 

1. What animal motors are used in the United States? 

2. How does the power developed by animal motors compare with that 
developed by all other forms of motors on American farms? (See Transac- 
tions American Society of Agricultural Engineers, vol. ix.) 

3. Give directions for determining the suitability of a draft horse for work 
as a farm motor. 

4. Make a study of the distribution in the weight of a draft horse and 
report how this will affect his ability to pull a load. 

5. What is the normal capacity of a draft horse and what is his maximum 
pulling capacity? 

6. A draft horse weighing 1,600 lb. will develop how much power when 
pulling 160 lb. and at the rate of 2)4 miles per hour? 

7. A farm horse weighing 1,200 lb. pulls a load of 120 lb. at the rate of 2 
miles per hour. How much power will this horse develop? 

8. What is the relation between the capacity for tractive effort and the 
speed at which a horse is travelling? 

9. Report in detail how the angle of trace affects the capacity of a draft 
animal. 

10. What determines the proper feed for draft animals? 

11. Give rations for a draft horse. 

12. Compare the horse and the mule as draft animals. 



CHAPTER XII 
MECHANICAL TRANSMISSION OF POWER 

While the transmission of power by electric means is advanc- 
ing rapidly, it is probable that for some time to come power from 
one machine to another will be transmitted by mechanical means. 

Mechanical transmission of power between different machines 
may be accomplished by means of: 

1. Belts. 

2. Chains. 

3. Ropes and cables. 

4. Friction gearing. 

5. Toothed gearing. 

6. Shafting. 

To the above list should be added cams, eccentrics, connect- 
ing rods, cranks and levers as means for transmitting power to 
the various parts of the same machine. 

Belts. — One of the most common methods of transmitting 
power is by means of leather, rubber, canvas, or composition 
belting. On account of slipping, the transmission of power 
with belts is not positive as is the case with gears. 

The simplest arrangement is to have the belt connect two pul- 
leys, one of which is the driver and the other is the driven. The 
belt may be open or crossed. In the first case the two pulleys 
turn in the same direction. Connecting two pulleys with a 
crossed belt reverses the direction of the driven. 

The power transmitted by a belt depends upon the adhesion 
between the belt and the pulley. For indoor work and under 
reasonably dry conditions, leather has proved to be the most 
satisfactory and reliable material for belts. It is, however, the 
most expensive and its use cannot be recommended for outside 
work in inclement weather. 

Leather Belts. — Leather belts are made up of short strips 
of oak-tanned leather, each strip varying from 44 to 6(Hn. in 
length. Before being tanned for belting purposes the head, neck, 
belly and tail portions of the hide are trimmed off. The remain- 

278 



MECHANICAL TRANSMISSION OF POWER 279 

der of the hide is divided into three portions from which the 
different grades of belting are secured. The best grade of belting 
comes from the center piece of the hide, after a strip is cut off 
crosswise from the shoulders. The second grade comes from the 
flanks, and the poorest grade from the shoulders. 

Leather belting is made of single thickness, and is designated as 
single-ply, or single-belt. Double-ply belting is made by con- 
necting the flesh sides of two thicknesses of leather. 

The cost of double belting is just twice that of single belting, 
but it has been found that it will transmit twice as much power 
and will last more than twice as long as single belting. Owing 
to the greater stiffness of double belting it will not conform to the 
surface of the pulley as readily as a single belt, and its use is lim- 
ited by the size of the pulley. Double belts generally are not used 
on pulleys less than 10 in. 

Rubber Belts. — These consist of one or more layers of cotton 
duck alternating with layers of vulcanized rubber. The adhesion 
of rubber belts is somewhat better than that of leather belts. 
Rubber belts also will stand heat, cold and moisture better than 
leather belts. The life of a rubber belt is much shorter than that 
of a leather belt and the coating of rubber is easily ruined by the 
application of oil. 

Canvas Belts. — Canvas belts are lighter than rubber belts. 
They are well-adapted for saw mills or for farm machinery where 
the belt is exposed to the weather. Canvas belts stretch and con- 
tract with temperature changes and are not durable. Painting 
improves canvas belts. 

Care of Belts. — Leather belts must be kept clean and free from 
dust, dirt and oil. Dampness will loosen the cement which is 
used in building up the belt. Some manufacturers have now a 
process of waterproofing leather belts, but this has not been 
extensively tried out. 

Most preparations called "belt dressing" contain rosin and are 
injurious to leather. If it is necessary to soften a leather belt, 
neat's-foot oil, tallow, or castor oil should be used. 

The hair side of a leather belt should be run next to the pulley, 
as this is the weaker side, and being smoother than the flesh side 
will adhere much better to the pulley. 

If possible, machinery should be so placed that the direction 



280 



FARM MOTORS 



of the belt motion is from the top of the driving to the top of 
the driven pulley, when the sag will increase the arc of contact. 

Rubber belts should run with the seam side out, and not next 
to the pulley. All animal greases and oils should be kept away 
from rubber belts. Boiled linseed oil may be applied, but this 
should be done sparingly. 

Belts will hold better when the pulleys are at long distances 
apart. Two pulleys connected by a belt should be spaced far 
enough apart so as to allow of a gentle sag to the slack side of 
the belt when in motion. This distance will be 10 to 15 ft. for 
narrow belts and small pulleys. In the case of wide belts work- 
ing on large pulleys the distance between driver and driven 




Pulley Side of Belt 




Outside of Belt 



Fig. 273.— Belt lacing. 



should be at least 20 ft. If too great a distance is used, the extra 
cost of the belt will be wasted and the extra weight of the belt 
will produce unsteady motion and great friction in the bearings. 

Method of Lacing Belts. — The strength of the belt depends not 
only on the quality of the material from which it is made, but 
also on the method used in connecting the ends. The ideal 
joint is a cement joint. Such a joint should be made only after 
the ends of a belt have been stretched in position over pulleys. 

Lacing made of rawhide is most commonly used. Metallic 
wire lacing also will give good results if the lace wire is hammered 



MECHANICAL TRANSMISSION OF POWER 281 



below the surface of the leather so as to prevent excessive wear on 
the lace, and if care is taken not to have two wires cross each other 
on the pulley side of the belt. Wire lacing makes a less clumsy 
joint and does not decrease the strength of the belt on account of 
large holes as does rawhide lacing. 

To cement a belt, a lap joint generally equal to the width of the 
belt is made by beveling the two ends, applying glue and then 
clamping the two ends together in the required position. 

Before a belt is laced the two ends should be made absolutely 
square, otherwise the belt will tend to run off the pulleys. One 
method of lacing a belt is illustrated in Fig. 273. 

Other methods of connecting the ends of a belt are by means of 
belt fasteners, rivets, staples and sewing. These methods are not 
recommended, as they will pull out in time and leave the belt 
ends ragged. 

Pulleys. — Pulleys are made of iron, 
pressed steel, wood and paper. Pulleys are 
either solid (Fig. 274) or split (Fig. 275). 
Large pulleys are usually of the split type. 

Pulleys designed to transmit power by 
belts usually are crowned; that is, the 
rim is rounded, so that the diameter is 
greater at the middle. When crowned 
pulleys are used, the belt will remain at 
the center of the pulley and will not run 
off. The width of the acting surface or 
face of a pulley always should be greater than that of the belt. 

In order to be able to start and to stop the driven pulley with- 
out interfering with the driver, a combination of tight and loose 
pulleys is often used. In this case one pulley is fastened to the 
shaft and transmits motion, while the other is loose on the shaft. 
The driving shaft carries a pulley which has a width equal to 
that of the tight and the loose pulleys put together. The belt 
when in motion can be shifted so that it will run over the tight or 
over the loose pulley, thus throwing machinery into or out of gear. 
Where tight and loose pulleys are employed, or in any case where 
the belt may be shifted, the pulleys are straight; that is, are built 
without crowning, in order that the belt may be moved easily 
from one pulley to the other. 




Fig. 274.— Solid pulley. 



282 



FARM MOTORS 



The average leather belt will not transmit its maximum force 
on account of slipping on the pulleys. The adhesion between 
the belt and the pulley can be increased by covering the pulley 





Fig. 275.— Split pulley. 





Fig. 276.— Stepped 
pulleys. 



Fig. 277. — Quarter-turn 
belt. 



with leather. This method of increasing the power transmitted 
should be used only in emergencies. A well-designed drive with 
the belts and the pulleys of proper size to transmit the desired 
power should not require pulley covering. 



MECHANICAL TRANSMISSION OF POWER 283 

Small pulleys are secured to the shaft by means of setscrews. 
Large pulleys are fastened to the shaft by keys, or sometimes by 
both keys and set screws. 

Stepped pulleys (Fig. 276) have several faces of different 
diameters on both the drivers A B and driven CD, for varying 
the speed of a shaft by means of a shifting belt. 

Method of Calculating Sizes of Pulleys. — If there is no slip 
in the belt, the speeds of two pulleys connected by a belt will 
vary inversely as the diameters of the pulleys. 




Fig. 278. — Sprocket wheels. 

Calling D the diameter of the driver, d the diameter of the 
driven, N the revolutions of the driver, and n the revolutions of 
the driven, the following equation holds : 

DN = dn 

(The product of the diameter of the driver and its revolutions 
must be equal to the product of the diameter of the driven and 
its revolutions.) 

As an illustration: A gasoline engine running at 300 r.p.m. 
has a belt pulley 20 in. in diameter. Calculate the size of the 
driven pulley if it is to run at 600 r.p.m. 
From the above equation 

_ 20 X 300 _ . 
d = ~^0^ = 10 m * 



284 



FARM MOTORS 



The above rule applies equally well to gears, only the num- 
ber of teeth in the gears is used instead of the diameters of the 
gears. For example, if the driving gear running at 100 r.p.m. 
has 80 teeth, the driven must have 40 teeth if it is to run at 
200 r.p.m. and 160 teeth if it is to run half as fast as the driver. 

Quarter-turn Belt. — Sometimes it becomes necessary to drive 
by means of a belt two pulleys which are at or nearly at right 
angles with each other. If this must be accomplished without 
the use of guide pulleys, as shown in Fig. 277, certain conditions 
are essential. If A is the driver, the follower B must be so placed, 
that the belt leaving the face of pulley A will lead to the center of 
the face of pulley B (Fig. 277) . This means that the belt must be 




Fig. 279. — Links for chain drive. 



delivered from each pulley in the plane of the pulley toward 
which it is running. If the direction of motion of the driver is 
reversed, the belt will be thrown from the pulleys. 

Chain Drives. — Chains made of metal are used to some extent 
for transmitting power. The chains run on sprocket wheels, 
which are provided with suitable projections (Fig. 278). 

Chain drives are more positive than belt drives and will operate 
in damp places. The disadvantages of chain drives are that 
they stretch, are noisy and are expensive to keep in repair. Fig. 
279 illustrates links for a chain drive, used in connection with 
motors. 

Chains for automobiles usually are supplied with rollers to 
reduce friction. 

Rope Transmission. — Rope drives offer the following advan- 
tages for power transmission: 

1. Power may be transmitted to much greater distances than 
is possible with belts. 



MECHANICAL TRANSMISSION OF POWER 285 

2. Driver and driven can be very close together. 

3. Power can be transmitted more readily to different floors 
of a building. This is advantageous in flour or cement mills. 




Fig. 280. — Pulley for rope drive. 

4. Shafts of driver and driven can be at any angle with each 
other. 

5. Drive is noiseless. 



>t .Wer 




Fig. 281.— Rope drive. 

6. Loss by slipping is very small. 

Hemp and cotton ropes are commonly used, these ropes running 
on cast-iron pulleys (Fig. 280) which are provided with grooves 



286 



FARM MOTORS 



upon their faces to keep the ropes in place. Wire ropes are used 
for the transmission of large power over great distances, and in 
connection with hoists, elevators, inclined railways and dredging 
machinery. 

In the United States the continuous system (Fig. 281) is most 
commonly used. In this case ropes are wound over the driving 
pulley A and driven pulley B several times. The traveling ten- 
sion carriage C keeps the ropes on the pulleys at the proper tension. 
This system is especially well-adapted for vertical and angle 
drives. 

Another method is to run independent ropes side by side in 
grooves of pulleys (Fig. 282). This system is called the multi- 




Fig. 282.— Rope drive. 



pie system and is used to some extent for transmitting large 
powers, where the shafts are very nearly parallel. The continu- 
ous system (Fig. 281) has a much wider range of application 
than the multiple system. 

Friction Gearing. — In the case of friction gearing the driver 
and driven are without teeth and pressed together, no belts or 
chains being used, and the power transmitted is due to the fric- 
tion between the surfaces of the two wheels. In order to reduce 
the slipping to a minimum and to prevent the pressure between 
the two wheels from being too great, one or both of the gears are 
made of some slightly yielding material like wood, leather, or 
paper, as shown in Figs. 283 and 284. If only one of the gears is 
made of wood or paper and the other of iron, the gear with the 
softer material must be the driver. 

Friction gears are made as spur gears (Fig. 283) if the axes 



MECHANICAL TRANSMISSION OF POWER 287 

to be connected are parallel. Bevel friction gears (Fig. 284) are 
used for connecting axes at right angles to each other. 




Fig. 283. — Friction gears. 

Another form of friction gears consists of grooves cut in the 
circumference of two wheels, the projections of one gear being 
forced into the grooves of the other. 




Fig. 284. — Friction gears. 

The disc and roller constitute another form of friction gearing. 
If the disc revolves at a uniform speed, the speed of the roller 
can be increased by moving it away from the center and decreased 



288 



FARM MOTORS 



by moving the roller toward the center of the disc. If the roller 
is moved past the center, its motion is reversed. 

The friction drive as applied to automobiles (Fig. 140) works 
on the principle of the disc and roller. A flat-faced disc A is 
attached to the crankshaft of the motor. The other part con- 
sists of a wheel B keyed to a shaft S parallel to the disc but free 
to move on the shaft. Speed changes and reversing can be ac- 
complished by shifting the wheel on the face of the disc. 

The objections to friction gears are: 

1. The drive is not positive, as there always must be some 
slipping. 

2. The transmission of power by friction gears produces ex- 
cessive pressures on bearings. 





Fig. 285. — Spur gear. 



Fig. 286. — Rack and pinion. 



Friction gears are used where the power to be transmitted is 
not very great and where changes of speed have to be made while 
the machinery is in motion, as is often the case with certain 
machine tools. 

Toothed Gearing. — This form of power transmission is em- 
ployed when a positive speed ratio is desired between the driver 
and the driven. 

The projections of one gear which mesh with those of another 
are called teeth. The term "cogs" is sometimes applied to 
teeth inserted in the wheel of another material than that of the 
body of the gear. 

Gears usually are made of cast iron. For rough work the gears 
are cast, while for accurate work cut gears, made in a special 
machine tool, are used. Noiseless gears are made of rawhide, 
compressed between brass or iron plates. Sometimes one of the 



MECHANICAL TRANSMISSION OF POWER 289 

gears is provided with removable wooden teeth to decrease 
noise. Rawhide gears must not be used in places where they may 
get wet and must not be lubricated. For most farm machinery 
cast-iron gears are used. 

Spur gears (Fig. 285) are used for transmitting power between 
parallel shafts. A combination of a gear meshing with teeth 





Fig. 287. — Annular gear. 



Fig. 288.— Bevel gears. 



cut on a straight rectangular piece (Fig. 286) is called a rack and 
pinion. An annular gear (Fig. 287) is a wheel with teeth cut on 
the inside. 





Fig. 289.— Worm and 
wheel. 



Fig. 290.— Shaft 
collar. 



Bevel gears (Fig. 288) are used for connecting two axes which 
intersect. 

In the worm and wheel (Fig. 289) the screw-like action of the 
worm A revolves the wheel B. The worm and wheel is used for 
making fine adjustments on instruments. It is also employed 
in connection with hoisting machinery, as by the proper propor- 

19 



290 



FARM MOTORS 



tioning of the screw great weights can be lifted on a drum con- 
nected on the same shaft with the worm wheel. The worm and 
wheel is also found on the steering mechanism of traction engines, 
as illustrated in Chapter VII. 

Shafting. — Shafting is either employed directly for transmit- 
ting power or is used in connection with pulleys and gears. 





Fig. 291.— Shaft coupling. 



Fig. 292.— Clutch 
coupling. 



Shafting is made of wrought iron or of steel. The better the 
material in the shafting, the more power it will be able to trans- 
mit. Also, the greater the speed at which the shaft is run, the 
more power will it transmit. The torsional strength of a shaft, 





Fig. 293.— Shaft hanger. 



Fig. 294.— Bracket. 



or the resistance which it offers to breaking by twisting, is propor- 
tional to the cube of its diameter. 

To prevent a shaft from moving endwise, a collar (Fig. 290) 
is fastened to the shaft by means of setscrews. 

To fasten two lengths of a shaft end to end, a coupling (Fig. 



MECHANICAL TRANSMISSION OF POWER 291 

291) is used. To be able to fasten or separate two lengths of 
shafting while they are revolving, a clutch coupling (Fig. 292) or 
a friction clutch, illustrated in another part of the book, should 
be used. 

The standard sizes of shafting are given in odd sixteenths of 
an inch, and advance by eighths. They can be obtained from 
%6 m - U P to 5)4 in. cold-rolled. Shafts above 5}4 in. usually are 
turned. 

Shafting is suspended from hangers (Fig. 293) placed on beams, 
floors, or ceilings. A bracket (Fig. 294) is used for suspending 
shafting from walls. Hangers and brackets are provided with 
bearings in which the shafting revolves. The collar (Fig. 290) 
should be placed on the shaft against the bearing. A sufficient 





Fig. 295. — Roller bearing. 



Fig. 296.— Ball bearing. 



number of hangers or brackets should be used to prevent the 
shaft from bending. 

The bearings used to carry shafting may be plain bearings, as 
illustrated in connection with the various types of motors. To 
reduce the frictional resistance of a plain bearing, a roller bearing 
or a ball bearing is used. In the roller bearing (Fig. 295) the 
shaft rolls on hardened steel rollers, while in the ball bearing 
(Fig. 296) the shaft revolves on balls placed in suitably designed 
grooves. Both roller and ball bearings are expensive and diffi- 
cult to keep in good order. 

In general, the work which can be accomplished by any motor 
depends not only on the quality of the motor, but also on the 
system used for transmitting the power of the motor to the 
machines where power is utilized. 



292 FARM MOTORS 

Problems: Chapter XII 

1. What are the different methods of transmitting power? 

2. Discuss the advantages of leather, rubber and canvas belting. 

3. What determines the spacing of pulleys which are connected by belts? 

4. Explain the different methods used for lacing belts. 

5. Why are pulleys crowned if they are to be used for transmitting power 
by belts? 

6. An electric motor which runs at a speed of 1,200 revolutions per minute 
is to be used for driving a line shaft at 200 revolutions per minute. If the 
motor has a 7-in. pulley, calculate the size of the pulley on the line shaft. 

7. A gasoline engine which operates at a speed of 350 revolutions per min- 
ute is to drive the following machines : a hay press, an ensilage cutter and a 
corn sheller. Find the best speeds at which these machines should operate 
and specify the sizes of pulleys on the line shaft and on the machines to be 
driven, if the gasoline engine has a 15-in. pulley. . 

8. Give clear sketch showing how the pulleys should be placed for a quar- 
ter-turn belt. 

9. What are the advantages of rope drives, of chain drives? 

10. Discuss the advantages and the disadvantages of friction gearing. 

11. Explain the differences, using clear sketches, between an annular gear, 
a bevel gear, a spur-gear rack, a worm and wheel. 

12. (a) Explain the functions of the following when used in connection 
with shafting : collar, coupling, hanger. 

(b) Discuss the advantages and the disadvantages of roller and ball 
bearings. 



INDEX 



B 



Action of electricity, 236 

Air required for combustion, 20 

Alcohol denatured, 76. 

fuel, 75-76 
Alternating current, 249-250 

magneto, 98-100 
Altitude and barometric pressure, 7 
American windmill, 221-222. 
Ammeter, 256 
Ampere, 236 
Angle valve, 30 
Animal motors, 3, 4, 272 

power, cost of, 277 
Anthracite coal, 19 
Armature, 251 

Atwater-Kent system, 151-152 
Automatic governors for steam en- 
gines, 52 
Automobile accessories, 160 

axles, 142-143 

carburetors, 148-149 

chassis, 123-124 

control system, 146 

ignition, 149-154 

lighting, 160 

lubrication, 154-155 

motors, 124-132 

parts, 123 

radiator, 128 

starters, 155-160 

steering systems, 143-146 

tires, 147-148 

transmission, 123, 134-139 
Automobiles, types compared, 122 

wheels, 147 
Auxiliary carburetor air valve, 

84 
Auxiliary exhaust port, 187 



Back-firing, 78 

Balanced valve, 48 

Ball bearing, 291 

Barometric pressure, 7 

Batteries, 239-248 

Baume scale, 74-75 

Belt lacings, 280 

Belts, 278-281 

Bevel gear differential, 140-141 

gears, 289 
Bituminous coal, 19 
Boiler, 22 

classification of, 23 

cleaning, 40 

feed pump, 22 

fire-tube, 23 

management of, 39 

operation, 40 

rating, 39 

setting, 22 

traction engine types, 169- 
170 
Brake horse-power, 10 
Brakes, 146-147. 
Breeching, 21 
British thermal unit, 12 
Buckeymobile, 58-59 



Calculation of horse-power, 8 
Canvas belts, 279 

Capacity of storage battery, 242-243 
Carburetors, 78-87 

automobile types, 148 

auxiliary air valve, 83 

concentric float-feed type, 82-83 

function of, 78 

jacketed types, 85 



293 



294 



INDEX 



Carburetors, kerosene, 86 

multiple jet, 85 

pump-feed type, 80-81 

traction engine types, 188-190 
Care of belts, 279 

electric generators, 269 

motors, 269 

gas engines, 119 

steam engines, 62-64 

traction engines, 203-208 

windmills, 233 
Caterpillar traction engine, 194-196 
Chain drives, 284 
Charging storage batteries, 243 
Chassis, 123-124 
Chimney draft, 37 
Chimneys, 21, 37-38 
Circuit breakers, 259-260 
Classification of gas engines, 66 

generators and motors, 252 
Clutches, 132-134, 176-177 
Coal, 19 
Coke, 20 
Combustion, 20 
Commercial value of fuels, 21 
Comparison of various motors, 3 
Compound steam engines, 50, 171 

wound generators, 254 
motors, 255 
Compression pressures'f or alcohol, 76 
Cone clutch, 133 
Connecting electric motors, method 

of, 262-263 
Cooling of automobile motors, 128- 
129 

gas engines, 87-91 

traction engines, 184-185 
Cost of animal power, 277 

farm electric light plants, 265 

power, 4 

traction engine power, 202 
engines, 181 

windmill power, 234 
Creeping-grip tractor, 194-196 
Crude petroleum distillates, 72-75 
Current required to operate lamps, 
238 



D 

Delco system, 151-154, 159 
Diesel cycle, 66 

engine, 103 
Differential, 123 

Differentials for automobiles, 139- 
141 
• traction engines, 177-180 
Direct current magneto, 97 

currents, 249 
Dome for boiler, 23 
Distribution of electricity, 255 
Draft horse, 272-273 
Drawbar horse-power, 10 
Dry battery, 241-242 
Dual ignition system, 149 
Dutch windmill, 221 



Eccentric, 43 

Economy of traction engines, 202 
Edison storage battery, 245-247 
Efficiency of engines, 66 
Eight-cylinder automobile motor, 

127 
Electric automobiles, 122 

condenser, 95 

conductors, 238 

distribution, 255 

generator, 248 

ignition system, 91-97 

light plants for farms, 265-267 

meters, 256 
Electricity, action of, 236 
Ell-head motor, 131-132 
En-bloc motor, 127-128 ' 
Energy, 7 

Erecting windmills, 230-233. 
Expanding clutch, 133 



Farm electric light plant, 265-267 
Feed for horses, 275-276 
pump, 32-34 



INDEX 



295 



Feed-water heaters, 36, 171, 174 

Firing methods, 38 

Flash point of gasoline, 73 

kerosene, 73 
Float-feed carburetor, 82-85 
Floats for carburetors, 85 
Force, 6 
Forced circulation cooling system, 

129 
Four-stroke cycle, 67 
Friction clutch, 123 

drive, 137-139 

gearing, 286-288 
Front automobile axles, 142 
Fuels, 19-21 

for gas engines, 71-76 
Furnace, 21 
Fuses, 257-259 



Gage cocks, 31 

Gases, 6 

Gas engine, 65 

cooling system, 87-91 
cycle, 66 
fuels, 71-76 

horizontal and vertical, 78- 
79 
ignition system, 91-97 
indicator cards, 68 
lubrication, 104^106 
fuel mixture, 65, 78 
parts, 76-78 
selection, 111-113 
producers, 65, 72 
traction engine ignition, 190 
motor, 182-184 
engines, 180 
Gasoline, 72-74 

automobile, 122-165 
engine uses, 107-111 
feed systems, 148 
fires, 73 
storage, 73 
Gate valve, 29 
Globe valve, 29 



Governing of gas engines, 106-108 
steam engines, 51-53 
windmills, 225 

Grades of coal, 19 

Grates for boiler furnaces, 26 

Gravity feed system, 148 

Grease cups, 55 



H 



Hammer-break igniter, 93 
Hangers, 291 
Heat, 11 

engines, 2 

of combustion of fuels, 21 

unit, 12 
Heavy oil engines, 103 
High-tension distributor, 150-151 

magneto, 100-101 
Hit-or-miss governor, 106 
Hitch for traction engines, 208 
Hopper-cooled engine, 79, 87 
Horizontal gas engine, 78 
Horse, 272 
Horse-power, 8 
Hot air engine, 2 

tube ignition, 91 
Hydraulic ram, 218-219 
Hydrometer, 73, 75, 244 



Ignition, 149-154 

dynamos, 97 

systems, 91-97, 190-191 

timing, 115 
Illuminating gas, 72 
Impulse water motors, 214-216 
Incandescent lamps, 238 
Indicator for steam engines, 8-9 
Indicated horse-power, 8 
Inductance coil, 92, 95-96 
Induction coil, 95-96 
Injectors, 35 

Installation of electric machinery, 
267 

gas engines, 113 



296 



INDEX 



Installation of steam engines, 60 

windmills, 230 
Internal combustion engine, 65 

efficiency, 66 
Interrupter, 102 



Jacket water temperature, 88, 120 
Jump-spark ignition, 94-97 



K 



Management of boilers, 39-40 
electric motors, 268-269 
traction engines, 203-208 

Master-vibrator system, 149-151 

Matter, 6 

Mechanical automobile starters,- 159 
equivalent of heat, 12 

Mixer valves, 80-82 

Motion, 6 

Motor cycles, 163, 166 
definition of, 1 

Motor-en-bloc, 127-128 







Motors for automobiles, 124-128 


Kerosene, 73, 75 




gas traction engines, 182-188 


carburetor, 86, 189 




steam traction engines, 17 


engine, 75 




175 


Kilowatt, 237 




Mule, 276 

Multiple disc clutch, 133 


L 




Multiple-jet carburetors, 85 


Lacing belts, 280-281 




N 


Lead storage battery, 243- 


-245 




Leather belts, 278 




Natural gas, 20, 72 


Lever safety valve, 30 




Non-freezing mixtures, 91 


Lignite fuel, 19 






Liquids, 6 




O 


Locomobile, 58 






Losses in steam engines, 


49 


Ohm's law, 237 


Low-tension magneto, 97 


-100 


Oil cooling, 90 


Lubrication for automobiles, 154- 


cups, 55 


155 




Oil engine efficiency, 66 


gas engines, 104-106 




engines, 103-104 


steam engines, 55 




Operating gas engines, 114-119 


traction engines, 203- 


■204 


traction engines, 203-208 



M 



Magneto alternating current, 98-100 

direct current, 97 

high tension, 100-101 

ignition, 149 

oscillating type, 99-100 
Magnetos, 97-101 
Make-and-break ignition system, 

92-94 
Management of automobiles, 160- 
165 



Oscillating magneto, 99-100 
Otto cycle, 66 
Ox, 276 



Parts of gas engines, 76-78 

of gasoline automobile, 123 
generators and motors, 250-251 
traction engines, 168-169 
windmills, 222 

Peat, 20 

Pelton water wheel, 214-215 



INDEX 



297 



Petroleum fuels, 20 
Pipe fittings, 27 

grades, 27 

sizes, 27 
Piping for boilers, 26 
Piston valve, 47 
Plain slide valve, 44, 47 
Planetary transmission, 136-137 
Pop safety valve, 30 
Poppett valve, 129-130 
Power, 7 

cost, 4 

of horses, 273-274 

of streams, 211-213 

of traction engines, 188 

of windmills, 234 

on farms, 4 

transmission, 278 
Pressure, 6 

Pressure-feed 'system, 148 
Primary battery, 240-242 
Priming of carburetor, 85 
Producer gas, 72 
Prony brake, 10 

Progressive transmission, 134-135 
Propeller shaft, 142 
Properties of steam, 18 
Pulleys, 281 

Pump-feed carburetor, 80-82 
Pumps for traction engines, 170- 
173 



Q 



Quarter-turn belt, 284 



R 



Radiators, 128, 185 
Ram, hydraulic, 218-219 
Rating of boilers, 39 

of traction engines, 202-203 
Rear automobile axle, 143 
Repairing traction engines, 207 
Return tubular boiler, 23 
Reversing mechanisms, 171-175 
Rheostats, 260 



Roller bearings, 291 
Rope transmission, 284 
Rotary valve motor, 130 
Rubber belts, 279 



Safety valves, 30, 40 
Selecting a gas engine, 111-113 

a horse, 272 
Selective transmission, 135-136 
Series-wound generators, 252-253 

motors, 252-253 
Setting engine on dead centre, 48 
Shafting, 290 
Shunt-wound generators, 252-253 

motors, 252-253 
Sight-feed automatic lubricator, 

56 
Size of pulleys, 283 

of steam engine, 44 
Sleeve-valve motor, 130 
Solids, 6 

Sources of energy, 1 
Spark plug, 96 
Specific gravity, 13-14 
of alcohol, 76 
of electrolyte, 244-245 
of gasoline, 73 
of kerosene, 75 
of petroleum fuels, 74 

heat, 12-14 
Speed of traction engine motors, 188 

engines, 203 
Spur gears, 289 
Spur-gear differential, 141 
Starting electric motors, 268 

gas engines, 116-117 

systems for automobiles, 155- 
159 

traction engines, 205-206 
States of matter, 6 
Steam automobiles, 122 

chest, 43 

engine, action of, 2, 42 
care of, 62-64 
description, 42 



298 



INDEX 



Steam engine details, 53 
governors, 51-53 
indicator, 8 
cards, 49 
installation, 60-61 
losses, 49 
size of, 44 
gages, 31 

generation theory, 16 
power plant, 21-23 
properties, 18 
separators, 57 
superheated, 17 

traction engine motor, 171-175 
traps, 32 
turbines, 59-60 
Steering column, 143-145 

of traction engines, 176 
Stepped pulleys, 283 
Storage batteries, 242-247 
Straw fuel, 169-171 
Superheated steam, 17 
Switches, 260-261 



Traction engine speeds, 203 

transmission, 168, 176-179, 191- 
194 

valve setting, 207-208 

wheels, 169 
Tractor cultivator, 200 
Transmission gears,|134-139, 191-194 

of power, 278 
Two-stroke cycle gas engines, 66, 

69, 71 
Types of traction, 194-196 

of windmills, 221 



U 



Universal joint, 141-142 
Uses of electric motors, 263-264 

gas engines, 108-111 

storage batteries, 242 
Users of traction engines, 196-201 

windmills, 234-235 



Tee-head motor, 132 
Temperature, 11 
Theory of steam generation, 16 
Thermometric scales, 11-12 
Thermo-syphon cooling system, 128 
Throttling gas-engine governor, 107 
Throttle control of automobiles, 

145-146 
Timers, 101-102 
Tires, 147-148 
Toothed gearing, 288-289 
Traction engine boilers, 169-170 

carburetors, 188-190 

development, 201-202 

differential, 177-180 

governors, 187-188 

hitch, 208 

parts, 168-169 

power plant, 168 

rating, 202-203 

reversing gears, 171-175 



Vacuum-feed system, 149 
Valve-in-the-head motor, 131-132 
Valve gear types for steam engines, 47 

setting, 48 
Valves, 28-30 

for automobile motors, 129-132 
Various motors compared, 3 
Vertical boilers, 25 

gas engines, 78-79 
Vibrator, 95 
Volt, 236 
Voltmeter, 256 

W 

Water column, 31 

motor, 211-215 

tube boiler, 26 

turbines, 216-218 
Watt, 236 

Wattmeter, 257-258 
Wet cells, 242 
Windmill brake, 226 



INDEX 299 

Windmill gearing, 225-226 Wind wheel, 223 

governor, 225 Wipe spark igniter, 93-94 

parts, 222 Wiring of batteries, 247-248 

power cost, 234 of electric meters, 257 

rudder, 224 Wood as fuel, 19 

towers, 226-230 Work, 7 

uses, 234 Worm and wheel, 289 



LIBRARY OF CONGRESS 



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